SOX2 and osteopetrosis: All hiPSC lines derived from osteopetrosis patients expressed alkaline phosphatase and other stemness markers (SSEA4, OCT3/4, TRA1-60, SOX2) as revealed by immunofluorescence staining, flow cytometry (SSEA4, OCT3/4) (Fig. 1a), and qRT-PCR (Fig. 2).