We found that siRNAs targeting the PKN proteins significantly decrease the abundance of the GSK3-phosphorylated form of CTNNB1 in A375 (Fig. 6C, compare expression of P(S33)-CTNNB1 in lanes 5–8 with that in lanes 1–4; quantification is in Fig. 6D, left panel) melanoma cells following stimulation with WNT3A. Here, CTNNB1 is linked to melanoma.