Overexpression of SHC proteins are associated with cancer mitogenesis, carcinogenesis and metastasis. This finding suggests that epigenetic silencing of MBD4 is an early step in colorectal carcinogenesis. A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis, the formation of cancer. This and other research implicates pepsin in carcinogenesis attributed to gastric reflux. The cancer stem cell hypothesis does not contradict earlier concepts of carcinogenesis. The resulting genomic instability directly contributes to carcinogenesis. This model of carcinogenesis is popular because it explains why cancers grow. These mechanisms are crucial in the process of carcinogenesis. Identification of these modifications play important role in carcinogenesis studies. More than one mutation is necessary for carcinogenesis. There are many implications that various PARPs are involved in preventing carcinogenesis. The effect of low doses of radiation on carcinogenesis also are disputed. MAO-A produces an amine oxidase, which is a class of enzyme known to affect carcinogenesis. Hands and feet are relatively resistant to other forms of radiation damage, such as carcinogenesis. This suggests direct and specific carcinogenesis.