Through an inducible RNAi lentiviral-based experimental system, we were able to assess, in breast and colon cancer lines, the MKK3 contribution in sustaining cancer cell proliferation, survival, invasion, as well as hampering the response to chemotherapeutic treatments [1,9] and tumor malignancy with xenograft models in nude mice [1,8,9]. The gene discussed is MAP2K3; the disease is malignant colon neoplasm.