Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal human cancers, with 5-year patient survival rates of <5%. Activating mutations in KRAS are the predominant oncogenic drivers of PDAC but are accompanied by additional lower frequency genetic alterations. Our group previously identified the guanine nucleotide exchange factor ARHGEF10 in a genomic screen for genes with copy number alterations that may synergize with oncogenic KRAS to promote PDAC carcinogenesis. In the present study we show that ARHGEF10 possesses putative tumor suppressor function in PDAC. ARHGEF10 expression is reduced in over 70% of PDAC cell lines, and copy number loss is documented in more than 30% of PDAC patient-derived xenografts. Loss of ARHGEF10 expression enhanced subcutaneous tumor growth in mouse models, while its exogenous expression greatly impaired tumorigenesis. Loss of ARHGEF10 expression also increased in vitro proliferation, invasion, and motility of PDAC cell lines, and enhanced their metastatic spread in orthotopic mouse models. Treatment of ARHGEF10-depleted cells with the inhibitor dasatinib reduced levels of phospho Src kinase and attenuated motility and invasion in vitro. Together, our data indicate that ARHGEF10 may function as a tumor suppressor in PDAC.