GAPDH and melanoma: Next, to determine whether PKN1 depletion regulates WNT3A-dependent transcriptional changes, we assessed the expression of the WNT3A target gene AXIN2. Following transfection of A375 malignant melanoma cells with siRNAs targeting PKN1 or a control sequence and subsequent treatment with several doses of WNT3A, we used quantitative PCR to quantify the relative abundance of AXIN2 relative to GAPDH. We found that the relative abundance of AXIN2 was increased in the cells transfected with PKN1 siRNAs at several doses of WNT3A (Fig. 3, left panel).