➢ATRA (10–20 μM) induced splicing of XBP1 mRNA in 1 h in HuH-7 cells (Iwao 2015) [17].➢ATRA (10–20 μM) induced accumulation of XBP1 protein in the nucleus of HuH-7 cells in 8 h (Iwao 2015) [17].✧In P19 embryonic carcinoma cells, ATRA induced the upregulation of several UPR-related genes (Atf6, Xbp1, Chop) (Saito 2023) [61]. The gene discussed is ATF6; the disease is embryonal carcinoma.