TET2 knockdown led to upregulation and activation of c-Kit. (A) mRNA levels (normalized to actin) of c-Kit, as assessed by qRT-PCR. (B) Representative western blot analysis of total c-Kit, p–c-Kit, and SHP-1. GAPDH was used as loading control. (C) Quantitative analysis of c-Kit, p–c-Kit, and SHP-1 from 3 independent experiments. (D) Effects of c-Kit inhibitor STI571 (0.5 μM) on proliferation of sorted luciferase and TET2-knockdown CFU-E cells. Dimethyl sulfoxide (DMSO) was used as control. (E-H) Effects of c-Kit inhibitor STI571 (0.5 μM) on differentiation of luciferase and TET2-knockdown CFU-E cells. Sorted luciferase and TET2-knockdown CFU-E cells were cultured for 13 days in the presence of DMSO or STI571. Expression of GPA (E) or band 3/α4 integrin (F) was examined by flow cytometry analysis. (G) Quantitative analysis of results shown in panel F from 3 independent experiments. (H) Representative cytospin images of erythroblasts. Note that the TET2-knockdown–induced impairment in differentiation was reversed by STI571 treatment. *P < .05, **P < .01, ***P < .001.