Bone marrow cells from KPM+ mice with APL demonstrate growth factor-independent colony forming activity and enhanced serial replating properties, and differentiate in response to ATRA in methylcellulose cultures. (A) Colony forming activity of KPM+, KM+, and nondiseased KP+ bone marrow cells in the presence (plus) or absence (minus) of growth factors (GF: IL-3, IL-6, SCF, EPO). Data shown are representative of 3 independent experiments. Values shown represent the mean of duplicate cultures from one representative experiment. (B) Serial replating activity of KPM+ bone marrow cells in the presence of growth factors. Data shown is representative of 3 independent experiments. Values shown are the mean of duplicate cultures from one representative experiment. (C) PCR for wild-type (WT) and oncogenic lox-K-ras G12D (Δ) K-ras alleles demonstrates presence of the oncogenic lox-K-ras G12D allele in individual methylcellulose colonies derived from KPM+ and KM+ bone marrow. M indicates molecular weight marker; c-, negative control DNA; c+, positive control DNA. (D) Quantitation of BFU-E, CFU-M, CFU-G, CFU-GM, and CFU-GEMM colonies from KPM+, KM+, and nondiseased KP+ bone marrow cultured in the presence of growth factors. Note predominance of CFU-G colonies derived from KPM+ and nondiseased KP+ bone marrow and CFU-M colonies from KM+ bone marrow. (E) Cytospins (Wright-Giemsa stain) of pooled methylcellulose colonies from KPM+ bone marrow cells cultures in the presence and absence of 1 μM ATRA. Original magnification, × 100.