SMAD4 and cancer: In the present study, we examined the correlation of activated GSK-3β with those tumor suppressor genes and found that pGSK-3β positively correlated with the expression of p53, APC (P = 0.002), PTEN (P = 0.006), MGMT (P < 0.001), Smad4 (P = 0.001), or KAI1 (P < 0.002), which were shown to be correlated with good gastric carcinoma prognosis and may act as negative regulators throughout the proliferation or progression of cancer cells [26].