3. Growth factors can induce apoptosis by binding to their respective receptors (RTKs). When activated, RTKs in turn activate the Ras, Raf, MEK, MAPK, MKK, ERK, Fos, JNKs, and Jun pathway, which can lead to the induction of ARF via gene upregulation. ARF in turn suppresses mdm2, a suppressor of p53 activity. The resulting increase in p53 activity can induce Bax, Mt, and thus apoptosis.

4. Adenomatous familial polyposis is caused by a truncated APC protein, which results from inherited mutations in the APC gene (Segditsas and Tomlinson, 2006). However, the activity of the wild-type or normal APC allele is usually sufficient to maintain tumor suppressor activity. For this reason, and because the wild-type allele is often found to have acquired somatic mutations, it is assumed that both alleles must be mutated before tumors can form. The vast majority of mutations found in colorectal tumors have retained 0 to 3...
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