Csf1, also known as macrophage colony-stimulating factor 1, is the primary growth factor essential for the control of monocyte and macrophage differentiation, survival, proliferation and renewal [3]. It is involved in the CSF1/CSF1R signaling pathway, which has significant biological importance in processes like bone remodeling, hematopoiesis, and the regulation of the tumor microenvironment [1,2]. Genetic models, such as KO/CKO mouse models, have been crucial for studying Csf1's functions.

In Csf1 CKOAdipoq mice (a conditional knockout model targeting marrow adipogenic lineage precursors), there was an increase in femoral trabecular bone mass and a decrease in osteoclasts in the femoral secondary spongiosa region, indicating that Csf1 from these precursors is required for osteoclast formation and hematopoiesis in bone [2]. In the context of cancer, in osteosarcoma orthotopic xenograft models, the CSF1R inhibitor PLX3397 suppressed primary tumor growth and lung metastasis, suggesting that targeting the CSF1/CSF1R pathway can impact cancer progression [1].

In conclusion, Csf1 plays essential roles in monocyte and macrophage-related functions, bone remodeling, and hematopoiesis. Studies using KO/CKO mouse models have provided insights into its role in bone-related diseases and cancer, highlighting its potential as a therapeutic target in these disease areas.