PMP22 and colorectal carcinoma: Once Wnt/β-catenin signaling is activated, PMP22 (peripheral myelin protein 22), an integral membrane glycoprotein, causes differentiation of gastric CSCs, whose mRNA levels decline dramatically.617 In contrast, tumor necrosis factor receptor-associated protein-1 inhibits the differentiation of CSCs by adjusting ubiquitination or phosphorylation of β-catenin in colorectal carcinoma.618