GNAO1 R209C mutation promotes ETV6-RUNX1⁺ leukemogenesis. (A) Representative images of the effects of ectopic expression of GNAO1 WT or R209C mutant on mouse spleen size at days 32 to 35 after injection. Reh cells expressing WT GNAO1, the R209C mutation, or a GFP control (GFP⁺) were injected into recipients through the tail vein. GFP⁻, negative GFP cell control. Images represent the results of 5 mice per group of 3 independent experiments. Scale bars, 1 cm. (B) Quantification of spleen weight in panel A. (C) Flow cytometry analysis of BM infiltration at days 32 to 35 after injection. (D) Quantification of BM infiltration in panel C. (E) Kaplan-Meier analyses of survival curves. Median survival (days): GFP⁺, 64; WT, 48; R209C, 40.5 (n = 15). Data are representative of 3 independent experiments with similar results. *P < .05, by log-rank test. (B,D) Data are expressed as the mean ± SD. *P < .05; **P < .01, by 2-tailed Student t test.