FEN1 and cancer: Finally the human RAD27 homolog FEN1 (Singh et al., 2008) and RAD52 (Lieberman et al., 2016), as well as many other genes involved in DNA replication, repair and recombination (Lahtz and Pfeifer, 2011; Chae et al., 2016), can be over- or under-expressed in human cancers thus producing genetic instability (Stratton et al., 2009).