PTGS2 and colorectal carcinoma: Additionally, the activation of Src and EGFR by Erb-B2 Receptor Tyrosine Kinase (ERBB4), which was reported to be upregulated in 43% of patients with CRC, results in the upregulation of cyclooxygenase 2 (COX2) expression, which enhances the proliferation of CRC cells [19,20].