Treatment with tocilizumab not only decreased markers of bone resorption (CTX and C-terminal crosslinking telopeptide of type I collagen generated by MMPs (ICTP)) in RA patients, but also significantly increased serum levels of markers for bone formation such as osteocalcin and procollagen type I N-propeptide (PINP) [44]. The gene discussed is CYP27A1; the disease is rheumatoid arthritis.