RFC3 Full-Length MS Protein Standard (NP_002906), Labeled with [U- 13C6, 15N4]-L-Arginine and [U- 13C6, 15N2]-L-Lysine, was produced in human 293 cells (HEK293) with fully chemically defined cell culture medium to obtain incorporation efficiency at Creative-Proteomics. The elongation of primed DNA templates by DNA polymerase delta and DNA polymerase epsilon requires the accessory proteins proliferating cell nuclear antigen (PCNA) and replication factor C (RFC). RFC, also named activator 1, is a protein complex consisting of five distinct subunits of 140, 40, 38, 37, and 36 kDa. This gene encodes the 38 kDa subunit. This subunit is essential for the interaction between the 140 kDa subunit and the core complex that consists of the 36, 37, and 40 kDa subunits. Alternatively spliced transcript variants encoding distinct isoforms have been described.