The purpose of this study is to determine whether or not adipocytes harvested directly from fat pads or induced from bone marrow in lean and obese mice exhibit a sex-dependent rapid response to vitamin D metabolite 1á,25(OH)2D3 and if so to elucidate if it is via an ERp60 receptor mediated signaling pathway. The role of 1á,25(OH)2D3 and specifically the membrane effect will be examined in two genetically distinct mice to see if their cells have a differing sensitivity. The results indicate that there are differing responses in adipocytes that are induced from bone marrow versus differentiated fat pad adipocytes, and the function of 1á,25(OH)2D3 is sex-specific in some cases. Additionally, all the adipocytes tested demonstrated a rapid response to 1á,25(OH)2D3; mRNA for nVDR and ERp60 were found in all cells however the only functional protein found in the plasma membrane was ERp60 indicating that it may be necessary for the rapid response whereas nVDR is not required.