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Cells with damaged DNA that cannot be repaired normally undergo apoptosis, a process in which the cell kills itself. Tumor cells have high levels of a protein (survivin) that inhibits apoptosis.
Normally, cells become differentiated and become capable of specific functions
Normal cells stop dividing when they become crowded because mitosis is inhibited when cells contact nearby cells. Cancer cells continue to divide and produce a mass of cells called a tumor.
Normal cells cling to neighboring cells, cancer cells do not.
Normal cells stop dividing when they become crowded because mitosis is inhibited when cells contact nearby cells. Cancer cells continue to divide and produce a mass of cells called a tumor.Ability to Penetrate the Lamina
The lamina is a noncellular barrier that is attached to cells that line the surfaces, internal cavities, and organs (epithelial tissue). Normally, cells cannot penetrate this barrier and therefore cannot invade neighboring tissues and organs.
The immune system can recognize foreign cells and invaders (bacteria, viruses, etc.) because they have proteins and other structures that are different from the body’s "self" markers.
Tumors need a blood supply for food and oxygen. Cancer cells release growth factors that cause nearby blood vessels to produce branches that grow into the cancerous tissue.
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