Answer: lithosphere
Explanation:
Apart of the earth upper mantle,
In adults, stem cells remain undifferentiated until they are needed to repair or replace other cells. Stem cells can produce cells that are identical to themselves.
Oncogenes are most like the gas pedal on a car, while tumor suppressor genes are most like the brakes on a car. Oncogenes and tumor suppressor genes are mutated in cancer cells.
Oncogenes are genes overexpressed in cells in which they should not be expressed, thereby leading to cancer.
Some examples of oncogenes are growth factors such as, for example, the Platelet-derived growth factor (PDGF) or Epidermal growth factor (EGF).
Conversely, tumor suppressor genes are genes that act to regulate cell division and replication, thereby their inactivation also leads to cancer.
A well-known example of a tumor suppressor gene is the p53 gene that acts to control cell division and apoptosis (programmed cell death).
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