The SOSS (Sensor of single-strand DNA) complex consists of multiple proteins that promote DNA repair and G2/M checkpoint downstream of the MRN (Mre11, Rad50 and Nbs1) complex. The complex is composed of SSBP1, INTS3 and C9orf80. Specifically, the SOSS complex binds to ssDNA at DNA lesions that influences diverse endpoints in the cellular DNA damage response. The complex is required for efficient homologous recombination-dependent repair of double-stranded breaks and ATM-dependent signaling pathways. C9orf80, also known as SOSS complex subunit C and Single-stranded DNA-binding protein-interacting protein 1 (SSBIP1), is a 104 amino acid nuclear protein that is a component of the SOSS complex. Upon DNA damage, C9orf80 along with other components of the SOSS complex migrate to the nucleus. There are two isoforms of C9orf80 that are produced as a result of alternative splicing events.