KRAS and malignant colon neoplasm: To explain our clinical findings, we conducted additional studies in Caco-2 colon cancer cells, which express wild-type KRAS. Targeted silencing of CIP2A using shCIP2A led to decreased expression of CIP2A, KRAS, and pERK (Figure 4a), and a concomitant decrease in cell proliferation (Figure 4b, P = 0.013).