PTGS2 and renal fibrosis: Although rhein has been widely demonstrated to protect against renal fibrosis (Zeng et al., 2014; Hu et al., 2019; He et al., 2020; Wu et al., 2020; Yu et al., 2020), only two previous studies have reported that rhein protected against renal fibrosis by inhibiting the NF-ƙB p65 protein expression (Liu et al., 2021b) and lincRNA-COX2/miR-150-5p/STAT1 axis (Hu et al., 2020b).