PDPK1 and cancer: Finally, our data showing that depletion of PKN1 increases WNT3A-dependent apoptosis in melanoma cells bolster previous data that PKN1 may be relevant to cancer biology: 1) the depletion of PKN1 also promotes programmed cell death in models of multiple myeloma (64), 2) PKN1 is overexpressed in prostate tumors (65) and in certain cohorts of malignant melanoma (Fig. 2B), and 3) PKN1 is a downstream effector of PDPK1, which is activated during phosphatidylinositol 3-kinase signaling (59).