CPA1 and neuroendocrine carcinoma: Additionally, REG1A and CPA1 show utility in diagnosing mixed pancreatic acinar cell carcinoma/acinar-neuroendocrine carcinoma [56]; notably, we show that CPA1 has the highest reduction in PanNETs, which is consistent with the absence of CPA1 immunohistostaining in PanNETs [57].