PECAM1 and Legg-Calve-Perthes disease: Li et al. (18) reported that LCPD patients usually have a high level of interleukin-6 in their plasma, and the high concentration of interleukin-6 can prompt human umbilical vein endothelial cells to secrete CD31+/CD42b− endothelial microparticles, which in turn promote endothelial cell apoptosis and endothelial dysfunction and inhibit angiogenesis.