ATF3 and gastric cancer: Importantly, ATF3 silencing markedly enhanced the expression of β-catenin at both the mRNA and protein levels, whereas ATF3 overexpression decreased β-catenin transcriptional activity and protein expression, suggesting that tumorigenicity of downregulated ATF3 in GC cells is mediated, at least in part, by upregulating Wnt/β-catenin signaling activity.