The substrate and decreases as the cell approaches the unconstrained surface with chemoattractant source. Because, when the cell reaches the surface with maximum chemoattractant concentration, it tends to adhere to and spread over that surface. However, in the case of chemotaxis cue with higher effective factor the cell again elongates in perpendicular direction to the imposed chemical gradient. doi:10.1371/journal.pone.0122094.gPLOS ONE | DOI:10.1371/journal.pone.0122094 March 30,21 /3D Num. Model of Cell Morphology during Mig. in Multi-Signaling Sub.Fig 13. Shape changes during cell migration in presence of electrotaxis within a substrate with stiffness gradient. A cell is exposed to a dcEF where the anode is located at x = 0 and the cathode at x = 400 m. It is supposed that the cell is attracted to the cathode pole. At the beginning, the cell is placed in one of the corners of the substrate near the anode and far from the cathode pole. Two EF strength are considered; E = 10 mV/mm (a and b) and E = 100 mV/ mm (c and d). For both cases, the cell migrates along the dcEF towards the surface in which the cathode pole is located. Depending on EF strength, the ultimate location of the cell PX-478 site centroid will be different so that for E = 10 mV/mm the cell centroid keeps moving around an IEP located at x = 379 ?3 m (b) whilePLOS ONE | DOI:10.1371/journal.pone.0122094 March 30,22 /3D Num. Model of Cell Morphology during Mig. in Multi-Signaling Sub.for saturation EF strength, E = 100 mV/mm, the position of the IEP moves further to the cathode pole to locate at x = 383 ?2 m (d). In the case of saturation EF strength (E = 100 mV/mm) the cell perfectly elongates on the surface of cathode pole without extending any protrusion (see also S5 and S6 Videos for low and high EF strengths, respectively). doi:10.1371/journal.pone.0122094.gof the cell (see Fig 8). Near the cathode pole in the presence of weak EF the cell may extend many protrusions in different directions but the change of the cell centroid position is trivial. This is not the case in presence of strong EF, the position of the cell centroid remains constant due to the domination EF role. The cell is even unable to send out any protrusion. This takes place because the strong EF Trichostatin A supplement provides a dominant directional signal to guide the migrating cell towards the cathode, dominating the effect of other forces. This is consistent with previous work presented by the same authors assuming constant spherical cell shape [67] where the cell became immobile when it reaches the cathode in the presence of stronger EF strength. EF induces morphological change in the migrating cell where for both cases the average cell elongation and CMI are higher than those of all the previous cases (Fig 14). In presence of electrotaxis the cell achieves the maximum elongation sooner than the other cases and it maintains the maximum amounts until it reaches the end of substrate. Therefore, a flat region can be seen in the fitted elongation and CMI curves (Fig 14). For both cases, near the cathode, the cell elongation and CMI decrease, because in the presence of dcEF the cell tends to spread on the surface where the cathodal pole is located. However, in case of strong EF the cell elongation and CMI again increases because the electrical force acting on the cell body is strong enough to cause the cell elongation perpendicularly to dcEF direction, leading increase in the cell elongation and CMI. It is noteworthy mentioning that for.The substrate and decreases as the cell approaches the unconstrained surface with chemoattractant source. Because, when the cell reaches the surface with maximum chemoattractant concentration, it tends to adhere to and spread over that surface. However, in the case of chemotaxis cue with higher effective factor the cell again elongates in perpendicular direction to the imposed chemical gradient. doi:10.1371/journal.pone.0122094.gPLOS ONE | DOI:10.1371/journal.pone.0122094 March 30,21 /3D Num. Model of Cell Morphology during Mig. in Multi-Signaling Sub.Fig 13. Shape changes during cell migration in presence of electrotaxis within a substrate with stiffness gradient. A cell is exposed to a dcEF where the anode is located at x = 0 and the cathode at x = 400 m. It is supposed that the cell is attracted to the cathode pole. At the beginning, the cell is placed in one of the corners of the substrate near the anode and far from the cathode pole. Two EF strength are considered; E = 10 mV/mm (a and b) and E = 100 mV/ mm (c and d). For both cases, the cell migrates along the dcEF towards the surface in which the cathode pole is located. Depending on EF strength, the ultimate location of the cell centroid will be different so that for E = 10 mV/mm the cell centroid keeps moving around an IEP located at x = 379 ?3 m (b) whilePLOS ONE | DOI:10.1371/journal.pone.0122094 March 30,22 /3D Num. Model of Cell Morphology during Mig. in Multi-Signaling Sub.for saturation EF strength, E = 100 mV/mm, the position of the IEP moves further to the cathode pole to locate at x = 383 ?2 m (d). In the case of saturation EF strength (E = 100 mV/mm) the cell perfectly elongates on the surface of cathode pole without extending any protrusion (see also S5 and S6 Videos for low and high EF strengths, respectively). doi:10.1371/journal.pone.0122094.gof the cell (see Fig 8). Near the cathode pole in the presence of weak EF the cell may extend many protrusions in different directions but the change of the cell centroid position is trivial. This is not the case in presence of strong EF, the position of the cell centroid remains constant due to the domination EF role. The cell is even unable to send out any protrusion. This takes place because the strong EF provides a dominant directional signal to guide the migrating cell towards the cathode, dominating the effect of other forces. This is consistent with previous work presented by the same authors assuming constant spherical cell shape [67] where the cell became immobile when it reaches the cathode in the presence of stronger EF strength. EF induces morphological change in the migrating cell where for both cases the average cell elongation and CMI are higher than those of all the previous cases (Fig 14). In presence of electrotaxis the cell achieves the maximum elongation sooner than the other cases and it maintains the maximum amounts until it reaches the end of substrate. Therefore, a flat region can be seen in the fitted elongation and CMI curves (Fig 14). For both cases, near the cathode, the cell elongation and CMI decrease, because in the presence of dcEF the cell tends to spread on the surface where the cathodal pole is located. However, in case of strong EF the cell elongation and CMI again increases because the electrical force acting on the cell body is strong enough to cause the cell elongation perpendicularly to dcEF direction, leading increase in the cell elongation and CMI. It is noteworthy mentioning that for.