It has been observed that cancer cells take in much more glucose than normal cells. In fact, labeled glucose can be used to detect cancerous tumors through PET scans. Explain the changes in the metabolism of cancer cells that cause them to use so much glucose. Include the following terms in your answer: flux, regulation, ATP, and oxygen.

Cancer cells are characterized by higher proliferation and replication of cells than normal cells. This causes a high demand for energy and nutrients. Cancer cells also thrive under hypoxic or low oxygen environment and they depend highly on glucose consumption for ATP production, that it, glycolysis is the main pathway for generating energy. Glucose transporters (GLUT's) are integral membrane proteins that mediate the flux of glucose in cells and have been implicated in cancer. For example GLUT2 has been found to be up-regulated in human carcinoma cells.