RAC1 and pancreatic adenocarcinoma: Pancreatic adenocarcinoma tissue microarrays (TMAs) were stained for MMP3, Rac1b (a tumorigenic splice isoform of Rac1 previously shown to be upregulated by MMP3 in pancreas, breast, and lung cancers [18, 20, 21]), collagen I, and H&E.