Fig. 4
From: How the mechanical microenvironment of stem cell growth affects their differentiation: a review
Maintenance of stem cell osteogenic factor homeostasis and maintenance of chondrocyte phenotype through the HIF-1 pathway. HIF-1α increases TWIST expression, which in turn regulates osteogenic differentiation. Mechanical stimulation also promotes TWIST and inhibits E2A; TWIST and E2A interact to activate p21. p21 has different regulatory effects on osteogenic factors. Also, p21 positively regulates the expression of TWIST and negatively regulates the expression of E2A. Hypoxia and HIF-1α maintain the chondrogenic phenotype of cells by preventing cell osteogenic differentiation