Expression of dominant-negative PKCα results in decreased invasiveness of cancer cells. Invasion analysis of A375m2 (A), K2 (B) and MDA-MB-231 (C) strains overexpressing wt PKCα or expressing dominant-negative PKCα. Cells were transfected with pCMV6 vector expressing either wt PKCα or dominant-negative PKCα and let to invade into 3D collagen for 48 hours. 3D collagen cross-sections were analyzed using NIS Elements software (Nikon) and average invasion depth was calculated and normalized to that of untreated cells. The invasion depth in each individual field of view was assessed as sum of invasion depths of individual cells divided by the total number of cells in the respective field of view (including cells on the top of collagen). Statistical significance (marked by asterisks) was evaluated using ANOVA followed by Tukey’s honest significant difference test.