['The cancerous inhibitor of protein phosphatase 2A (CIP2A) oncoprotein is overexpressed in colon cancer tissue compared to normal colon mucosa. We investigated the impact of CIP2A on colon cancer.', 'A tissue microarray consisting of 167 colon cancer specimens was investigated. The association between CIP2A and clinicopathological parameters was analyzed using the χ(2) test. Survival was analyzed using the Kaplan-Meier method. The impact of CIP2A on proliferation and drug resistance was evaluated using the 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide test. An anchorage-independent colony formation assay was also performed.', 'CIP2A was an independent prognostic factor in colon cancer after controlling for other clinical confounding factors, such as stage and lymphovascular invasion, particularly in stages III and IV (hazard ratio\u2009=\u20092.974, P\u2009<\u20090.001). The knockdown of CIP2A reduced the proliferation and anchorage-independent colony formation of colon cancer cells. Knockdown of CIP2A decreased the resistance of the cells to 5-fluorouracil, oxaliplatin, and SN38 (an active metabolite of irinotecan). Treatment with 5-fluorouracil, oxaliplatin, and SN38 decreased CIP2A expression.'] Is cIP2A a predictor of poor prognosis in colon cancer?