Several other cell lines in the panel known to have mutations in the KRAS gene (e.g. Colo 320DM, SK-CO-1, SNU-C2B, SW403, SW620, SW837, SW1116) or BRAF (e.g. HT-29, LS411, RKO) also display low Erk activity; see also http://www.sanger.ac.uk/genetics/CGP/CellLines), further supporting a key role for additional modifiers in determining the activity of Erk1/2 within a subset of CRC cell lines. The gene discussed is MAPK1; the disease is colorectal carcinoma.