CDKL2 and brain neoplasm: Knockout mice data have indicated a role for CDKL2 in cognitive function.19, 20, 21, 22 According to the publicly available Oncomine database, the CDKL2 level in nontumor tissues is higher than that in tumor tissues in all reported cancer types (including brain tumor, colorectal cancer, kidney cancer, lung cancer, and breast cancer).