Final answer:
Cancer cells can inhibit the process of apoptosis in normal cells, allowing them to continue dividing uncontrollably, which can lead to tumor formation. This is due to genetic mutations disrupting the regulation of the cell cycle.
Step-by-step explanation:
Cancer cells can convert normal cells into cancerous cells or prevent apoptosis from occurring in normal cells. Apoptosis is the process by which cells undergo programmed cell death when they are no longer needed or are damaged beyond repair. In cases where cancer cells prevent apoptosis, the damaged cells can continue to divide and form a mass known as a tumor. This uncontrolled cell division is a hallmark of cancer. Mutated cells that should undergo apoptosis fail to do so due to reasons such as mutations preventing initiation of apoptosis signaling, loss of expression of apoptosis receptors, or overexpression of growth factor pathways that inhibit apoptosis.
Normal cells become cancerous when genes regulating cell growth, such as proto-oncogenes and tumor-suppressor genes, are altered through mutations. The impaired regulation leads to an inability to control the cell cycle, causing cells to proliferate uncontrollably and often lose differentiation capabilities. This unchecked growth combined with evasion from apoptosis can lead to the spread of the cancerous cells and the formation of tumors.