Figure 24-9. The seven types of proteins that participate in controlling cell growth.

Figure 24-9The seven types of proteins that participate in controlling cell growth

Cancer can result from expression of mutant forms of these proteins: growth factors (I), growthfactor receptors (II), signal-transduction proteins (III), transcription factors (IV), pro- or anti-apoptotic proteins (V), cellcycle control proteins (VI), and DNArepair proteins (VII). Mutations changing the structure or expression of proteins in classes I – IV generally give rise to dominantly active oncogenes. The class VI proteins mainly act as tumor suppressors; mutations in the genes encoding these proteins act recessively to release cells from control and surveillance, greatly increasing the probability that the mutant cells will become tumor cells. Class VII mutations greatly increase the probability of mutations in the other classes. Virus-encoded proteins that activate growth-factor receptors (Ia) also can induce cancer.

From: Section 24.2, Proto-Oncogenes and Tumor-Suppressor Genes

Cover of Molecular Cell Biology
Molecular Cell Biology. 4th edition.
Lodish H, Berk A, Zipursky SL, et al.
New York: W. H. Freeman; 2000.
Copyright © 2000, W. H. Freeman and Company.

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