CDK1 and esophageal squamous cell carcinoma: After CKAP2L knockdown in ESCC cells, the results of western blot analysis validated that CKAP2L induced the expression of cyclin B1 and CDK1, whereas CKAP2L-OE up-regulated the expression of cyclin B1 and CDK1 in comparison to the Vector group (Figure 5(e)).