N-Ras^G12Dand Tet2^+/−collaborate to enhance cytokine response in HSPCs. (A) Total number of cells generated from 100 FACS-sorted HSCs after a 10-day culture (left) or from 500 HSCs after a 6-day culture (right) with SCF and/or TPO (n = 3). (B) Phosphorylated FACS analysis of STAT5 activation in LSKs. Whole BM cells were starved at 37°C for 30 minutes and then stimulated with TPO (6.25 ng/mL) for 15 minutes. The percentage of phosphorylated STAT5⁺ cells within the mutant LSK compartment was normalized to that of WT. Data represent mean ± standard error of the mean. Two-tailed Student t tests were used to assess statistical significance. *P ≤ .05, **P ≤ .01.