Proposed leptin signaling pathway in adipose Sca-1+/CD45-/CD34+MSC cells. Post leptin-leptin receptor binding and receptor-receptor dimerization, JAK-2 is phosphorylated. Activation of JAK-2 results in phosphorylation of PI3K which lead to phosphorylation of Akt and ERK1/2. Leptin-induced increase in phosphorylated ERK1/2 induces activation of STAT3 by phosphorylating Ser 727 amino acid residue. Under basal condition, alternative STAT3 Tyr 705 gets phosphorylated. Consequently, activated STAT3 translocates to nucleus and induces MCP-1 gene transcription in Sca-1+/CD45-/CD34+ MSC cells.