KRAS and neoplasm: Because tumor-repopulating activity in Kras; p16p19null tumors resides within the Kras-expressing, GFP+ subset of tumor cells descended from virally infected satellite cells (Figure S1 in Supplementary Material), Kras; p16p19null tumor cells were sorted for transplantation from two Kras; p16p19null primary tumors as GFP+, Pi−, Calcein+ cells.