To test the roles of Fstl1 in GBM cells response to chemotherapy, A172 cells (TMZ-sensitive cells lacking MGMT expression; Supplementary Fig. 2A and C), U87 cells (MGMT promoter hypermethylation, Supplementary Fig. 2B), and D54 cells (MGMT promoter hypomethylation) were infected with lentivirus expressing Fstl1 or vector control (Supplementary Fig. 3A). The gene discussed is FSTL1; the disease is glioblastoma.