Also available in 1 mg, 2 mg, 5 mg, 25 mg, 50 mg, 100 mg, 500 mg and bulk. Please contact Fisher for quotes. ISRIB (trans-isomer) is a potent inhibitor of PERK (IC50=5 nM) that restores protein translation and prevents SG formation in the presence of P-eIF2alpha. Purity 98.81%