Second site KrasD12 mutant alleles induce hypersensitive myeloid progenitor growth and initiate T-ALL. (A) CFU-GM formation by fetal liver cells expressing WT Kras (●), KrasD12 (▪), KrasD12/G37 (▲), or KrasD12/G64 (♦). Mean ± standard error of the mean (SEM) of 5 independent experiments is shown. Data points marked with an asterisk (*) are significantly different from WT by paired, 1-tailed t test (P < .05). (B) Signaling in transfected COS-7 cells under basal (B), starved (S), and EGF-stimulated (E) conditions. (C) Signaling in transduced S49 cells under starved conditions. These cells were infected with MSCV-GFP-Kras vectors and sorted to equalize Ras expression levels. GFP-K-Ras fusion proteins run at a different molecular weight than endogenous Ras proteins. (D) Morphology of 3T3 cells expressing WT Kras, KrasD12, KrasD12/G37, or KrasD12/G64. Note that KrasD12 and KrasD12/G64 induce morphologic changes. (E) Survival of lethally irradiated WT mice transplanted with bone marrow cells transduced with MIG vector (×; n = 8) or MIG vectors expressing WT Kras (●; n = 10), KrasD12 (▪; n = 9), KrasD12/G37 (▲; n = 15), or KrasD12/G64 (♦; n = 14). (F) White blood cell (WBC) counts at death in recipients of bone marrow transduced with MIG vector (n = 8), KrasD12/G37 (n = 15), or KrasD12/G64 (n = 14) viruses. Data plotted as mean ± SEM, with an asterisk (*) indicating data points significantly different from WT by unpaired, 1-tailed t test (P < .05). (G) Peripheral blood smear showing blast morphology in a mouse with T-ALL.
