HIF1A and osteosarcoma: We used a HIF-1-dependent luciferase reporter assay constructedin human osteosarcoma U2OS cells (U2OS-HRE-Luc), where the formationof HIF-1 increases the expression of luciferase under hypoxic conditions.19 The initial testing showed no activity fromthese peptides, which was attributed to their potential lack of cellpermeability.