Accordingly, we observed that in basal conditions ovarian and osteosarcoma CDDP resistant cells are characterized by a fragmented mitochondrial phenotype, associated with increased expression of the pro-fission proteins Drp-1, h-FIS1, MFFs and downregulation of the mitochondrial fusion mediators OPA1 and Mfn1. This evidence concerns the gene PROS1 and osteosarcoma.