DDIT3 and amelogenesis imperfecta type 1G: As shown in Figures 7(a) and 7(b), compared with the significantly increased protein and mRNA levels of CHOP and GRP78 in the LPS group (both P < 0.05), APS pretreatment significantly decreased the expression levels of CHOP and GRP78 (both P < 0.05), which indicates that APS can inhibit the occurrence of ERS reaction.