EIF2AK3 and hematologic disorder: PERK, encoded by the EIF2AK3 gene, is expressed ubiquitously in normal tissues (albeit at higher levels in secretory tissues such a pancreatic islet cells) [10] and is also present and active in hematologic malignancies, including multiple myeloma (MM) [11] and chronic myeloid leukemia (CML) [12].