Myeloid progenitors from CMML mice show abnormal growth pattern in semisolid culture. (A) A quantity of 5 × 10⁴ bone marrow cells isolated from CMML mice and control mice were plated in duplicate in semisolid medium with or without GM-CSF. The data are presented as average percentages (from multiple CMML-like and control mice) of maximum number of colonies formed in culture with 0.2 ng/mL of GM-CSF. Photomicrographs (original magnification ×20) showed control and CMML myeloid progenitor colonies grown in different concentrations of GM-CSF. Student t test was performed. Error bars show SDs. Asterisks indicate P < .002. (B) Analysis of myeloid progenitors in bone marrow cells isolated from CMML and control mice. Percentages of myeloid progenitors (IL-7Rα^– Lin^– Sca1^– c-Kit⁺ cells), common myeloid progenitors (CMPs; FcγR^lo/− CD34⁺), GMPs (FcγR^hi CD34⁺), and megakaryocyte erythroid progenitors (MEPs; FcγR^loCD34^–) relative to total bone marrow cells are indicated. (C-D) Quantitative analysis of myeloid progenitor compartment in control mice (n = 6) and CMML mice (n = 11). Results are presented as averages + SD. Student t test was performed. Asterisks indicate P < .05.