Loss of a c-Myb allele does not affect the frequency of hematopoietic progenitors. (A) Western blot analysis of c-Myb expression in enriched Lin⁻ and Lin⁻Sca-1⁺Kit⁺ cells from c-Myb^f/f and c-Myb^f/d mice. GRB2 expression served as a control. (B) Frequency of Lin⁻Kit⁺, Lin⁻Sca-1⁺, and Lin⁻Sca-1⁺Kit⁺ cells (Q1, Q3, and Q2) in enriched Lin⁻ cells of c-Myb^f/f and c-Myb^f/d mice, assessed by use of PE-conjugated anti–Sca-1 and APC-conjugated anti–c-Kit antibodies on enriched Lin⁻ marrow cells. (C) Flow cytometric analysis of c-Kit expression in Lin⁻Sca-1⁺Kit⁺ cells from c-Myb^f/f and c-Myb^f/d mice. Representative of 3 experiments.