Loss of TET3 negatively affects K562 erythroid differentiation potential and chromatin stability. (A) Representative images of benzidine-hematoxylin staining of K562 TET3^WT and TET3^ΔS1+S2 cells. Benzidine staining (brown) differentiates hemoglobin-positive (Hb⁺) and hemoglobin-negative (Hb⁻) cells. Scale bars indicate 50 μm. (B) Quantification of Hb+ cells under normoxia vs hypoxia in parental K562 cells and TET3ΔS1/ΔS2 lines. (C) Quantification of cells with high hemoglobin levels under normoxia vs hypoxia in parental K562 cells and TET3ΔS1/ΔS2 lines. Normoxic butyrate-treated cells were used to establish the range of benzidine staining intensity in each replicate. High hemoglobin cells were defined as having higher benzidine staining intensity than 50% of Hb+ cells in the normoxic butyrate-treated cells. (D) Quantification of cells with pyknotic nuclei in normoxia vs hypoxia, with or without sodium butyrate, in parental K562 cells and TET3ΔS1/ΔS2 lines. (E) Quantification of cells with karyorrhectic nuclei in normoxia vs hypoxia, with or without sodium butyrate, in parental K562 cells and TET3ΔS1/ΔS2 lines. N = 3 for all hypoxia/sodium butyrate treatments. A minimum of 500 cells were counted in each replicate for each treatment combination. *P < .05; **P < .01; ***P < .001.