The Ras-related superfamily of guanine nucleotide binding proteins includes the R-Ras, Rap, Ral/Rec and Rho/Rab subfamilies all of which are thought to play an important role in either endocytosis or in biosynthetic protein transport. The process of transporting newly synthesized proteins from the endoplasmic reticulum (ER) to various stacks of the Golgi complex and to secretory vesicles involves the movement of carrier vesicles and requires Rab protein function. Rab proteins are also an integral part of endocytic pathways. Rab 20 (Ras-related protein Rab-20) is a 234 amino acid protein that localizes to the golgi apparatus and belongs to the Rab subfamily of small GTPases. Expressed in normal and cancerous pancreatic tissue, Rab 20 plays an important role in apical endocytosis and recycling and may be involved in the development of exocrine pancreatic adenocarcinomas.
