Procollagen type III migrated close to the proα1 of procollagen type I and their levels in OI cultured medium were significantly lower compared to the normal, while an increase is evident after the treatment of OI cells with RA at concentrations of 0.1, 1, 10 μM, and extracts (RE and LBE) at concentrations of 0.1, 1, and 10 μg/mL each (Figure 6A). Here, COL1A2 is linked to osteogenesis imperfecta.