ITIH4 and osteosarcoma: Because the number of osteoblasts is decreased in HIV-infected patients, and Gp120 has been shown to have pro-apoptotic effects on multiple cell types, we first sought to determine whether Gp120 induces apoptosis in human immortalized fetal osteoblasts (FOB cells) and human osteoblast-like osteosarcoma cells (U2OS cells) that were cultured in the presence or absence of recombinant HIV strain IIIB derived Gp120 over several days.