AXIN1 and melanoma: Additionally, knockdown of ERK1 and ERK2 in the presence of WNT3A markedly decreased abundance of the critical intracellular Wnt/β-catenin antagonist AXIN1 (Figure 5B), paralleling observations seen with pharmacological inhibition of BRAF and MEK and validating our prior siRNA-based identification of MAPK3 and MAPK1 as candidate regulators of Wnt/β-catenin signaling in melanoma cells [27], [29].