Western Blot results showed that the protein expression of CDK4, CDK6, CyclinD1, RB1, and p-RB1 was decreased compared with that of the control group, and it can be concluded that neferine inhibits the phosphorylation of the downstream RB1 and thus inhibits the proliferation of gastric cancer cells by affecting the expression of CDK4/CDK6/CyclinD1 complex, as shown in Fig 8B. Here, CDK4 is linked to gastric cancer.