Facts on File Encyclopedia of Health and Medicine

naling proteins, act as messengers within the cell.
When proto-oncogenes mutate, their genetic
instructions become garbled. The protein produc-
tion they regulate changes. The cell may produce
too many proteins that instruct it to grow, or not
enough proteins that instruct it to stop growing.
In either circumstance the cell’s growth becomes
excessive.
Oncogenes do not alone cause cancer, though
researchers remain uncertain about the extent to
which they influence the development of cancer.
Other genetic and environmental factors come
into play, affecting various aspects of cellular
growth. Mutations may occur in the genes that
regulate DNArepair, for example, allowing dam-
aged cells to replicate. Researchers believe it is
the convergence of factors, the emergence of

oncogenes among them that permits cancer to

develop.

IDENTIFIED ONCOGENES

Gene Cancer Connection

bcl-2 B-cell lymphoma and numerous other cancers

c-erb BREAST CANCER

c-myc small-cell LUNG CANCER(SCLA), Burkitt’s

lymphoma

HER-2/neu breast cancer

hTERT numerous cancers

ras numerous cancers

src breast cancer, colon cancer, SCLA,

neuroblastoma, rhabdomyosarcoma

See also CELL STRUCTURE AND FUNCTION; TUMOR

SUPPRESSOR GENES.

oncogenes 385