The interaction of PKN3 with RhoC promotes malignant growth

► Inducible PKN3 knockdown inhibits primary prostate and breast tumor growth. ► PKN3 associates with Rho-family GTPases, and preferentially with RhoC. ► RhoC predominantly associates with PKN3 compared to other PKN family members. ► PKN3 catalytic activity is stimulated in the presence of RhoA and RhoC. ► Turn-motif phosphorylation at T860 closely correlates with PKN3 activity.