Once the RNA-DNA primer is synthesized, replication factor C (RFC) initiates a reaction called "polymerase switching"; pol delta, the processive enzyme, replaces pol alpha, the priming enzyme. RFC binds to the 3'-end of the RNA-DNA primer on the Primosome, to displace the pol alpha primase complex. The binding of RFC triggers the binding of the primer recognition complex (Tsurimoto and Stillman 1991, Maga et al. 2000, Mossi et al. 2000). RFC is recruited to telomeres via interaction with 5'-phosphate ends of a telomere repeat sequence (Uchiumi et al. 1996, Uchiumi et al. 1999). In budding yeast, the alternative evolutionarily conserved RFC complex in which the RFC1 subunit is substituted with the CTF18 complex (composed of CHTF18, CHTF8 and DSCC1) plays a critical role in telomere maintenance (Hiraga et al. 2006, Gao et al. 2014). The CTF18-RFC complex is also implicated in telomere maintenance in fission yeast (Khair et al. 2010). It was shown that the human CTF18-RFC complex has a redundant function with the RFC pentamer in PCNA loading and DNA replication (Bermudez et al. 2003), but its role in human telomere maintenance has not been studied. Mouse CFT18 complex is necessary for proper development of germ cells (Berkowitz et al. 2012).