HIPK2 and malignant colon neoplasm: RKO colon cancer cells, carrying wild-type p53, stably transfected with siRNA control vector (RKO-C) or with siRNA p53 vector (RKO-p53i), and T98G glioblastoma cells, carrying mutant p53, were transfected with HIPK2 or its catalytic inactive mutant K221R.