Figure 1: Model of GR and MR action: the adipogenic media contain DEXA, IBMX, and insulin and are supplemented with fetal bovine serum. Upon corticosteroid hormone binding to its receptor (GR or MR) FKBP51 is exchanged for FKBP52 that facilitates the retrograde movement of the NR towards the nucleus. IBMX increases cAMP leading to PKA activation that triggers the translocation of FKBP51 from mitochondria to the nucleus, possibly upon changes in its phosphorylation status. In the nucleus GR binds to its target genes, localizing in the NL (nuclear lamina) and possibly in the NM (nuclear matrix). FKBP51 is retained in the nucleus by its interaction with the NL, the NM, and chromatin, regulating GR-target genes and possibly other genes.