KIT is variably expressed in human colon tumors, xenografts, and cell lines. A) An array of primary and xenograft tumor sections was scored for KIT immunostaining intensity (n = 316 total sections, n = 137 primary tumors only; bar = 50 μm). B) The number of primary tumors and xenografts per score was tallied. C) Selective images from the tumor array demonstrating heterogeneity of KIT immunoreactivity (bar = 50 μm). D) FACS plots for CD44 and KIT of colon cancer cell lines (DLD1, LS174T, COLO320DM, HT29, SW620, CACO2) and patient-derived xenografts (UM-COLON#8, POP77). Percentage of cells in each quadrant is shown.