Introduction: Despite calcium-activated Cl- channels (CaCCs) were first described over 3 decades ago, the molecular identity of CaCCs has recently been identified. These channels are widely expressed in various cell types and tissues which are expressed in various cell types including tracheal, intestinal, and glandular epithelia, smooth muscle cells, intestinal pacemaker cells, sensory neurons, and several tumors. Interestingly, over-expression of TMEM16A /ANO1 has been found in many tumor types including breast cancer, and head and neck cancer. However, the expression and function of TMEM16A in gastrointestinal cancer, such as pancreatic cancer, has not been revealed. Pancreatic cancer is the eighth leading cause of cancer death and is difficult to treat because clinical presentation is often late, and the disease is resistant to conventional chemotherapy. About 57% of pancreatic cancer patients are diagnosed at distant metastasis status and five-year survival rate is only 2%. More than 90% of pancreatic cancer has activating mutations in KRAS and recent exome sequencing studies have identified additional mutations in several kinds of genes such as AIRD1A, ARID1B, SMARCA1. However, most of mutational genes are tumor suppressor genes and these are no effective druggable target in pancreatic cancer. Hence, the study for new druggable target is unmet medical need. Method: PANC-1, ASPC-1 and BXPC-3 cells were used as pancreatic tumor cell lines and hTERT-HPNE cell line was employed control pancreatic cell line from ATCC. The coding regions of human TMEM16A/ANO1 (ac isoform) sub-cloned into the pEGFP-N1 mammalian expressible plasmid and pLVX-AcGFP-N1 without a C-terminal GFP using BamH1 and Xho1 restriction enzymes. Intracellular chloride concentration was measured with a chloride sensing fluorescent, triple mutant YFP (H148Q/I152L/F46L) on PANC-1 cells. Results: To explore the function and mechanism of TMEM16A/ANO1 in pancreatic cancer, we carried out MTT assay and immunoblotting at TMEM16A/ANO1 over-expressed pancreatic cells. Pancreatic tumor cells death and proliferation by TMEM16A/ANO1 was regulated by extracellular chloride concentration. In addition, the molecular mechanism of these effects was proved by immunoblotting in pancreatic cancer cell lines. Conclusion: In this study, we show that TMEM16A/ANO1channel promotes cell proliferation in pancreatic cancer cell lines and intracellular chloride through TMEM16A/ANO1 is important mechanism for cell proliferation. These results indicate that TMEM16A/ANO1 can be possible druggable targets using ANO1/TMEM16A inhibitor. Further, TMEM16A/ANO1 might play a role as prognostic factors for survival outcomes in pancreatic cancer.