CSF‐1R, the surface receptor that binds M‐CSF, is expressed by some leukemia cells (Romine et al, 2021; Simonis et al, 2021), while CSF‐1R‐expressing resident macrophages in bone marrow are requested for the persistent engraftment of long‐term reconstituting hematopoietic stem cells (Kaur et al, 2018). The gene discussed is CSF1R; the disease is leukemia.