The origin of the remaining two were uninterpretable, with one of these latter signatures dominated by T > G mutations in the GpTpG context and the other signature highly correlated with COSMIC signature 5, which has been found in all cancer types (Alexandrov et al., 2013) and has been suggested to display clock-like properties suggestive of an association with the aging process (Alexandrov et al., 2015). This evidence concerns the gene CLOCK and cancer.