Asacomplexpathologicprocess,tumorigenesishas involvedvariousregulatingmechanismsatmolecular and cellular levels, particularly tightly related to DNA damage. In previous issues of JMCB, we have published several papers highlighting the relationship between tumorigenesis and DNA damage. As a guest editor, Dr Shen has organized a special issue on genomic instability and cancer (Shen, 2011). In addition, two related JMCB collections were published in last year (Wu, 2012) and early this year (Wu, 2013). The collection of four papers published in this issue will add more data and insights into this area. It is well known that epigenetic dysfunction such as the inhibition of different DNA repair components