MMP2 and polyostotic fibrous dysplasia: To investigate which signaling pathway was decisive in the PFD-induced increase in the expression of MMP-2/9, we evaluated AKT, ERK, p38, SRC, FAK, and STAT3 phosphorylation levels, and found that PFD may activate the p38, FAK, STAT3, ERK, and SRC pathways to promote the expression of MMP-2 and MMP-9 proteins.