Fig. 7

Proposed inhibitory feedback loop for MSC osteogenesis. We propose that phosphoinositide 3-kinase (PI3K)/Akt activation is a key signaling event required for the induction of osteogenesis in human bone marrow MSCs. As osteogenesis progresses, Cav-1 is upregulated as a negative feedback mechanism to suppress continued osteogenesis. PI3K/Akt signaling is one pathway that Cav-1 suppresses within caveolar membrane rafts to achieve this end, and as osteogenesis progresses more phosphorylated Akt (p-Akt) is translocated to this subcellular compartment