PAX5 promotes development of B220⁺CD19⁺ pro-B cells in vitro. LSK cells transduced with either control or PAX5-containing vector were cultured in SFM supplemented with SCF, FL, and IL-7 for 14 days. (A) Expression of B220, CD19, and GR-1/MAC-1 on cells already gated as YFP/GFP⁺. Representative profiles from 3 independent experiments. (B) Mean percentages (SD) of transduced cells expressing YFP/GFP, B220, CD19, and GR-1/MAC-1 from 3 independent experiments. *P < .05. (C) Typical coexpression profiles of B220 together with CD43, BP-1, CD24, CD25, and IgM on cells produced in control (top panels) and PAX5 (bottom panels) transduced cultures. Representative profiles from 3 independent experiments.