Mouse BM-MSCs express HPSE1 and can be enzymatically inhibited by OGT2115. (A) RT-PCR indicated the existence of mRNA of Hpse1 in mouse BM-MSCs throughout serial passages. (B) Immunocytochemistry demonstrated the existence of HPSE1 protein (red) in the mouse BM-MSCs, in which the nuclei were counter-stained by DAPI (blue). (C) Western blot indicated that enzymatically active form (50 kDa) of HPSE1 could be detected in mouse BM-MSCs. Gapdh was used as a loading control. (D, E) Dot blot assay of mouse BM-MSCs demonstrated mild reactivity against 10E4 indicating a mild reservation of intact heparan sulfate glycosaminoglycans. The small molecule HPSE inhibitor, OGT2115, can repress the enzymatic activity of HPSE indicated by the statistically stronger reactivity of 10E4.