CSF1 and prostate cancer: It is tempting to propose that this modification of the pre-metastatic niche by prostate cancer cells is due to factors secreted by ST6GAL1 overexpressing cells (including CSF1), the ability of extracellular ST6GAL1 to modify sialylation and cell signalling pathways in recipient cells in the pre-metastatic niche, or a combination of these functions.