A chemical substance that causes cancer is called a chemical carcinogen. Some of the chemical carcinogens contained in tobacco smoke. These carcinogens cause several kinds of cancer, as indicated in the figure. A lymphoma is a solid tumor composed of T or B lymphocytes. A carcinoma is a type of cancer derived from epithelial cells.
Cancers occur when signaling pathways are perturbed.
The molecular apparatus known as the cell cycle clock collects the messages and decides whether the cell should divide.