SPP1 and Familial prostate cancer: Indeed, based on their gene expression profiles, myCAFs and iCAFs partially resemble myofibroblasts and quiescent HSCs, respectively; both myCAFs and myofibroblasts are characterized by the expression of Acta2, collagen-related genes, Fgfr1, and Spp1, while iCAFs and quiescent HSCs express Des, Fgfr2, and Lrat. 19,36 Notably, Spp1/OPN+Col1a1+ CAFs have also been identified in castration-resistant prostate cancer, where the Spp1/OPN-ERK signaling axis has been implicated in driving therapeutic resistance.39