ABCG2 and glioblastoma: In line with this current result, previous studies demonstrated that expressions of ALDH1A1 as well as stemness genes (e.g., ABCG2 and NOTCH1) increased in response to TMZ treatment in GBM cells (Chua et al., 2008; Schäfer et al., 2012; Tango et al., 2018; Alves et al., 2021).