KIT and leukemia: To examine the leukemogenic potential of different subpopulations, splenic leukemia cells from the second generation of TR mice were sorted into four fractions according to the expression level of c-kit and Gr-1, namely c-Kit+Gr-1low (Fr 1), c-Kit+Gr-1high (Fr 2), c-Kit-Gr-1low (Fr 3), and c-Kit-Gr-1high (Fr 4) (Fig. 4a).