Through the results of IHC, the CRC tissues with low ID4 expression presented more proliferation and metastasis-related proteins (upregulated CDK4, cyclin D1, ki-67, and Vimentin and downregulated E-cadherin) and less apoptosis-related proteins (upregulated Bcl-2 and downregulated caspase-3) than CRC tissues with high ID4 expression (Figure 6). Here, CDK4 is linked to colorectal carcinoma.