Loss of ARID3a impairs B lineage development from human cord blood HSPCs. A. HSPCs were seeded into HSC culture media supplemented with SCF, FLT3 and TPO (triplicates of 10,000 cells/well) for 48 hours, prior to treatment with polybrene only, or lentivirus containing either ARID3a-specific, or scramble-control shRNA. A portion of cells were assessed for ARID3a knockdown after 48 hours. B. Following virus treatment, cells were maintained for one month in media supplemented with conditioned feeder media, G-CSF, IL7, SCF, and FLT3 for B lineage development. Representative flow cytometry data indicate the gating strategy used for B lymphocyte subsets and monocytes from virus treated samples. C. Percentage of B lineage pre-pro B cells (CD34+ CD33− CD10+ CD19−), pro-B cells (CD34+ CD33− CD10+ CD19+), pre-B cells (CD34− CD33− CD10+ CD19+) and B cells (CD34− CD33− CD10− CD19+)) for no virus control, ARID3a shRNA, and scramble control cultures are shown. Means and SE for 4 independent experiments are shown. Statistical significance was determined by unpaired t test: **, p=0.0032; ***, p=0.0002; ****, p<0.0001.