**4. Biochemical signaling pathways that regulate the bone formation**

Bone formation is controlled by numerous elements including transcription factors, hormones, growth factors, oxidative processes, mechanical loading, stress, bone fractures and aging [32]. Osteoblasts and osteoclasts are able to read these external stimulants and propagate the biochemical signals via various signaling cascades. The biological response of the selected signaling pathways results either in bone formation or disruption. Some of the crucial pathways operating in the osteoblasts and osteoclasts are described as follows:
