A matrix vesicle is a small extracellular vesicle equipped with membrane transporters and enzymes involved in mineralization, such as tissue nonspecific alkaline phosphatase (TNAP) [5,6], ectonucleotide pyrophosphatase/phosphodiesterase (ENPP) [7], sodium-dependent phosphate cotransporter type III (Slc20a1/Pit1 and Slc20a2/Pit2) [8,9,10,11,12], phosphoethanolamine phosphohydrolase 1 (PHOSPHO1) [13,14,15], and ankylosis (ANK) [16,17]. Here, SLC20A1 is linked to ankylosis.