For example, lung tumours of tobacco smokers (but not of nonsmokers) contain a high percentage of G to T transversions in TP53 at several hotspot locations (in particular, at codons 157, 158, 175, 245, 248 and 273) characteristic of PAHs present in tobacco smoke.(Denissenko et al. 1996) Of note, hotspot mutations found at codons 175, 248, 249 and 273 together account for over 25 % of all missense mutations identified in human cancers (Olivier et al. 2010). Here, TP53 is linked to cancer.