HSPA5 and glioblastoma: On the other hand, Tsai et al. reported that ER stress-inducible isochaihulactone, a natural compound extracted from herb induces apoptosis through induction of DDIT3 (CHOP), which is independent of GRP78 and PERK expression in glioblastoma multiform cells, indicating the existence of CHOP-mediated apoptosis pathway which is independent of the canonical ER stress signaling46.