In osteosarcoma, upregulation of ATF6 and E2F7 during sustained ERS suppressed E2F1 expression, upregulation of E2F7 was dependent on activation of XBP1, and downregulation of E2F1 enhanced Noxa and Puma expression and promoted ER stress-induced apoptosis [57]. Here, XBP1 is linked to osteosarcoma.