Numbers of GMP are reduced in Btk-deficient mice. (A) Bone marrow cells obtained from femurs and tibias were stained for lineage markers, Kit, Sca1, CD34, and FcRγII/III. The Lin⁻Sca1⁻Kit⁺ (MP = myeloid progenitor) population in the bone marrow was further analyzed for myeloid progenitor subpopulations CMP, GMP, and MEP by the expression of CD34 and FcRγII/III, and the LSK population for the expression of CD48 and CD150. Cells from the bone marrow of wild-type (wt) and Btk-ko mice were stained and analyzed by flow cytometry. Hematopoietic precursor subpopulations are shown as percentage of whole bone marrow cells (B,D) or as absolute numbers per femur (C,E). Data presented are mean values (± SD). *P ≤ 0.05. n represents the number of biological replicates.