Abstract: ObjectiveTo evaluate the correlation of CDK4protein expression in the cytoplasm with the clinicopathologic
features and prognosis of lung cancer.MethodsImmunohistochemistry was employed to examine CDK4protein expression in
the cytoplasm of lung cancer samples, using normal lung tissue samples as control. The correlation of cytoplasmic CDK4
protein expression with the clinicopathologic parameters and prognosis of lung cancer patients was analyzed.ResultsNo
significant difference was found in cytoplasmic CDK4protein expression levels between lung cancer and normal lung tissues
(P=1.000). In the lung cancer tissues, however, an increased cytoplasmic expression of CDK4was positively correlated with the
clinical stages and lymph node metastasis. Prognostic analysis showed that the patients with an increased cytoplasmic CDK4
expression had a markedly shorter overall survival than those with a low cytoplasmic CDK4expression. Multivariate analysis
suggested that the level of cytoplasmic CDK4expression was an independent prognostic indicator for the survival of patients
with lung cancer (P<0.001).ConclusionOverexpression of CDK4protein in the cytoplasm may promote the carcinogenesis of
lung cancer and can be an unfavorable prognostic factor for the survival of lung cancer patients.