SEL1L and central nervous system cancer: On the contrary, valproic acid, a histone deacetylase inhibitor that is another promising chemotherapeutic agent, induced UPR by upregulating the expression of BiP, CHOP and Sel1L in glioma stem cells [176] and the chemical chaperone 4-phenyl butyric acid, an ERS inhibitor, reduced the cytotoxic effect of chemotherapeutics [137].