“…We then investigated pro-cath-D internalization by LRP1 using MEF that lacked M6P receptors ( Figure 1B Pro-cath-D and ectopic cath-D do not modulate LRP1b-chain tyrosine phosphorylation in fibroblasts The LRP1 at the plasma membrane is located in clathrin-coated pits and lipid rafts (Boucher et al, 2002;Zhang et al, 2004;Wu and Gonias, 2005), and it has been suggested that there are LRP1-induced signal transduction pathways triggered by tyrosine phosphorylation or RIP in lipid rafts (Boucher et al, 2002; von Cathepsin D, endocytosis and LRP1 RIP D Derocq et al Arnim et al, 2005;Wu and Gonias, 2005). We observed that LRP1b overproduction directs pro-cath-D to the lipid rafts (Beaujouin et al, 2010), suggesting that cath-D modulates the tyrosine phosphorylation of LRP1, as shown for the PDGF-BB (Boucher et al, 2002;Loukinova et al, 2002;Boucher and Gotthardt, 2004;Newton et al, 2005) and CTGF (Yang et al, 2004) growth factors, the tPA serine protease (Hu et al, 2006) and in fibroblasts transformed with v-Src (Barnes et al, 2001(Barnes et al, , 2003. We next investigated the effect of pro-cath-D on the tyrosine phosphorylation of LRP1b in fibroblasts.…”