SPP1 and Calcium oxalate nephrolithiasis: In addition, the up-regulation of OPN also increases the heterogeneity of crystals and promotes the formation of stones, OPN combines with calcium phosphate to act as a matrix for stones, these matrix proteins also play a role in stopping to dissolve the calcium phosphate and inhibiting the accumulation and growth of crystals, and provide a form of aggregation and adhesion for free calcium ions in urine, therefore, oxalate or oxalate ions gradually formed nucleation on its surface and eventually formed calcium oxalate kidney stone [41].