Similar to our findings in LG-GSCs, reduced Abcg1 protein expression using two different shRNA targeting constructs in two independently-generated NPcis glioblastoma lines (K1861 and K4622) increased the expression of CHOP, a final effector of the ER stress response, and resulted in higher levels of tumor cell death by apoptosis. Here, ABCG1 is linked to glioblastoma.