SAMD1 inhibits erythropoiesis and promotes Kit signaling in human CD34⁺ HSPCs. (A) Representative flow cytometry plot of anti-CD71 PE and anti-CD235a APC at days 12 and 17 of erythroid differentiation. (B) Quantitation of early erythroid (CD71^high) and late erythroid (CD71⁺ CD235a⁺ and CD71⁻ CD235a⁺) cells at day 12 of differentiation as determined by flow cytometry (n = 12). (C) Flow cytometric quantitation of mature erythrocytes (CD235a⁺) at day 17 of differentiation (n = 12). (D) Flow cytometric quantitation of the %max MFI in SCF-treated samples vs vehicle-treated controls at 5 minutes after SCF stimulation in the Kit⁺ CD71⁺ population at day 12 of erythroid differentiation (n = 8). (E) Representative flow cytometry gating strategy of Kit⁺ CD71^low, CD71^medium, and CD71^high day-12 CD34⁺ HSPCs stimulated with SCF. (F) Representative plot of pERK (pThr202/pTyr204) MFI in the absence and presence of SCF stimulation in the Kit⁺ CD71^medium population at day 12 of erythroid differentiation. (G) Quantitation of the %max MFI in SCF-treated samples vs vehicle-treated controls at 5 minutes after SCF stimulation in the Kit⁺ CD71l^ow, CD71^medium, and CD71^high populations at day 12 of erythroid differentiation as determined by flow cytometry (n = 8). Error bars represent SD or standard error of the mean (SEM). ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001 (2-tailed unpaired Student t test). %max, percentage of maximum; FSC-H, forward scatter-height; MFI, median fluorescence intensity; ns, not significant.