ABCG2 and glioblastoma: Results revealed a significant reduction in TMZ sensitivity in TMZ‐resistant GBM cells, accompanied by a substantial increase in the expression of major vault protein‐(MVP), O6‐methylguanine‐DNA‐methyltransferase‐(MGMT), and ATP‐binding‐cassette transporter‐G2‐(ABCG2).