To elucidate the role of CD79a-expressing myeloid cells on primary tumor formation, two myeloid cell populations (Ly6C+CD79a− and Ly6C+ CD79a+) were sorted from BM cells of 4T1-tumor bearing SCID (Balb/c) mice harvested 20 days after tumor cell innoculation. The gene discussed is CD79A; the disease is neoplasm.