The gene EIF2AK3 transcribes the protein PERK, an important kinase involved in the ER stress response, specifically the unfolded protein response. Misfolded proteins are a hallmark of numerous neurodegenerative diseases, and PERK’s downstream signaling eventually leads to phosphorylation of eIF2α to initiate the integrated stress response (ISR) and global translation inhibition under homeostatic conditions. However, excessive PERK activation can eventually lead to initiation of pro-apoptotic pathways. Interestingly, our understanding of PERK regulation at the protein level is well-characterized, but little is known about the transcriptional regulation of EIF2AK3. We have shown the existence of three alternatively spliced transcripts in cortical neuroglial rat cultures under ER stress via thapsigargin. Further, we were able to separate these transcripts and performed Sanger sequencing analysis to identify isoforms with both intron retention (EIF2AK3_Int2) and loss of exon fragments (EIF2AK3_∆Ex5A and EIF2AK3_∆Ex5B). We also investigated how ER stress affected expression of alternative transcripts in human monocyte-derived macrophages (MDMs), discovering alternatively-spliced human isoforms 5 and 11. Finally, we performed qPCR using TaqMan probes targeting the main PERK and EIF2AK3_Int2 isoforms, and found both had a statistically significant increase in the context of increasing TG incubation time (p<0.05). These results have shown the existence of alternative splice regulation in the EIF2AK3 gene, and future studies must be conducted to further characterize these isoforms, how they function in the context of ER stress, and if there are any other isoforms produced during different kinds of stress.