MAP2K3 and colonic neoplasm: To evaluate the MKK3 role in more physiological experimental models, we explored in vitro and in vivo HT29 cancer cell response to 5-fluorouracil (5-FU), a commonly used chemotherapeutic drug in colon cancer patients.33 In accordance to the above data with ADR, HT29 clonogenic cell survival was markedly and dose-dependently reduced after 5-FU treatment, compared with drug-treated control cells (sh/scr; Figure 6a).