JAK2 and neoplasm: On the other hand, in OE33 cells of esophageal carcinoma, leptin promotes the activation of the JAK2, ERK, and Akt signaling pathways, which induce the expression and activation of cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), EP-4 receptor, and EGFR transactivation, events that contribute to tumor progression [198].