In our experiments Cav-1 role in IGF-IR recycling remains to be clarified: in fact Cav-1 down regulation consistently slowed the rate of IGF-IR recycling but this effect was not statistically significant. The increase in PTRF-IGF-IR immunoprecipitation till 15 min and the effect of PTRF/Cavin silencing on IGF-IR levels suggest that PTRF/Cavin could have a different and specific role compared to Cav-1. We can hypothesize that PTRF/Cavin could play a role during surface IGF-IR recovery and that it could participate to complex mechanisms that regulate recycling. The decrease IGF-IR rate of replacement following PTRF/Cavin silencing in presence of IGF-I, could be related also to increase degradation. Mepiroxol Nevertheless we did not observe any change of IGFIR expression following Cav-1 and PTRF/Cavin silencing during IGF1treatment. Previous studies have demonstrated that down regulation of PTRF/Cavin reduces the stability of Cav-1 and that the absence of Cav-1 causes a decrease expression of PTRF/Cavin. Here we show that Cav-1 and PTRF/Cavin silencing in Hacat cells did not induce any significant reciprocal change in their expression pattern. We can not exclude that later time points after silencing should be required to observe a significant change in the reciprocal expression of these proteins. In conclusion we show for the first time that PTRF/Cavin interacts with IGF-IR and play a role on IGF-IR internalization. Cav-1 and PTRF/Cavin regulate in a distinct manner the balance of surface IGF-IR levels following IGF-I. Then Cav-1 and PTRF/ Cavin could represent distinct targets to down regulate IGF-IR action. Type 1 diabetes is an autoimmune disease, in which the b-cells in the islets of Langerhans are specifically destroyed. The disease is currently treated with multiple daily injections of insulin, however it is very difficult using exogenous insulin to prevent Baohuoside-I hypoglycaemic episodes and the debilitating late complications of the disease. Islet transplantation may represent a potential form of treatment, but the poor availability of donor tissue prevents its widespread use.