CDK2AP1 and squamous cell carcinoma: It has been shown that Cdk2ap1 is activated by TGF-β-Smad2 and mediates TGF-β induced growth arrest in normal diploid cells and the loss of Cdk2ap1 expression in squamous cell carcinoma is correlated with disrupted TGF-β-Smad signaling pathway [9], [11].