SPP1 and fibrosarcoma: Interestingly, the increased osteopontin adhesion in CD44s-Separate cells disagrees with a previous conclusion that CD44 variants, but not CD44s, facilitated osteopontin binding to allow migration[29]; however, these data were based on rat pancreatic carcinoma, rat fibrosarcoma, and mouse melanoma cells, and pertained to CD44v4-7, not CD44v7-10.