EIF2AK3 and hepatocellular carcinoma: More recently, Mahammeed et al. reported that nelfinavir was highly effective to inhibit the growth of HCC cells in vitro and in vivo when combined with the PERK inhibitor ISRIB, which is an experimental drug that inhibits the integrated stress response (ISR); the ISR is a term that encompasses the phosphorylation of eIF2α not only by PERK, but also by other kinases including PKR, GCN2 and HRI [59].