CDK4 and lung carcinoma: However, we observed that the expression level of CDK4 was positively correlated with the status of pathology classification(P = 0.047) lymph node metastasis (N classification) (N0-N1 vs. N2-N3) (P = 0.007), and clinical stage (I-II vs. III-IV) (P = 0.004) in lung cancer patients (Table 2).