CSF1 and prostate cancer: CSF1, also known as macrophage colony stimulating factor (MCSF), is crucial for the function and differentiation of myeloid lineage cells including osteoclasts and monocytes/macrophages61 and is implicated in sustaining the functions of tumour-associated macrophages (TAMs) and resistance to immune checkpoint blockade.62, 63, 64, 65 As ST6GAL1 overexpressing prostate cancer cells have increased secretion of CSF1, we next used co-culture models to assess the potential effects of prostate cancer cells on osteoclasts and macrophages.