Fig. 1.

The many facets of peroxisome proliferator-activated receptor (PPAR)γ, a nuclear receptor and transcription factor. PPARγ expression and activity is dependent on heterodimerization with RXRs, binding of endogenous or exogenous ligands, other transcription factors, posttranslational modifications such as phosphorylation or ubiquitination, and cell-autonomous circadian rhythms. PPARγ has three main functions: adipocyte differentiation, insulin sensitivity, and lineage allocation of mesenchymal stem cell (MSCs). All three are important for the skeleton and are ligand dependent.