Effects of substrate stiffness on the (A) filopodial density and (B) averaged filopodial length for individual cancer cells.

<p>The filopodial density was defined as the number of filopodia per unit length of the cellular perimeter. The filopodial length was averaged from all visible filopodia of the cell. The bars represent the means of the variables and the errors denote the standard deviations calculated from 33, 18, and 43 cells for the PVC 1∶1, PVC 3∶1, and glass substrates respectively. Significant differences were found between the data of PVC 1∶1 and 3∶1, and PVC 1∶1 and glass with that ** indicates <i>p</i><0.01.