HSPB1 and glioblastoma: However, when the GBM cells were first treated with quercetin, which blocks both Hsp27 and COX-2, the combination of t-AUCB and quercetin displayed better antiproliferative effects compared to monotherapy with t-AUCB, suggesting a significant role of Hsp27 and COX-2 in t-AUCB resistance.