RPA4 Full-Length MS Protein Standard (NP_037479), 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. This gene encodes a single-stranded DNA-binding protein that is the 30-kDa subunit of the replication protein A complex. Replication protein A is an essential factor for DNA double-strand break repair and cell cycle checkpoint activation. The encoded protein localizes to DNA repair foci and may be involved in the cellular DNA damage response. This protein may also play a role in inhibiting viral replication.