NGF and osteoporosis: NGF binds to TrkA and p75NTR receptors on the surface of osteoclast precursor cells, activates the NF-κB and MAPK signalling pathways, significantly upregulates the expression of RANKL, and promotes the differentiation of osteoclast precursor cells to mature osteoblasts, which exacerbates bone resorption in osteoporosis models.