Functional characterization of the SH2B3 D231fs allele. (A) Western blot analysis of SH2B3 expression and JAK-STAT signaling in lymphoblastoid cells from the proband (noted as SH2B3 D231fs/D231fs*), the affected sibling (SH2B3 D231fs/D231fs), and an SH2B3 wild-type healthy control. (B) Western blot analysis of SH2B3 expression and JAK-STAT signaling in JURKAT T-ALL cells expressing SH2B3 targeting shRNAs (pLKO-shSH2B3) or an inactive control shRNA (pLKO-shCTRL). (C) Differential growth curves of SH2B3 wild-type and patient-derived SH2B3 mutant lymphoblastoid cells grown in 1% fetal bovine serum (FBS) containing media. (D) CFSE dilution analysis of cell cycle kinetics in SH2B3 patient-derived SH2B3 mutant lymphoblastoid cells in 1% FBS containing media. (E) Differential cell growth of SH2B3 wild-type and patient-derived SH2B3 mutant lymphoblastoid cells in standard (10% FBS) and low serum (1% FBS) conditions. Experiments shown were performed at least twice, and quantitative assays were performed in triplicate.