SPP1 and osteoporosis: [29]. In another recent study, increased osteopontin plasma levels in MS patients correlated with the bone-specific degradation product C-telopeptide of type-I collagen [30]. However, Altintas et al. [31], by introducing osteopontin as a shared cytokine in the pathogenesis of MS and osteoporosis, reported lower levels of circulating osteopontin in MS patients with osteoporosis at the femoral neck.