To further clarify the specific mechanisms responsible for the regulation of tumor growth by aberrant CDK4 expression, we established Cdk4-deficient MCA205 mouse fibrosarcoma cell line and Cdk4-deficient TC1 mouse lung epithelial cell line by CRISPR/Cas9 technology with Cdk4 specific sgRNA pairs. The gene discussed is CDK4; the disease is fibrosarcoma.