How do T-cells work to recognize invading cells or molecules?

Antigen-presenting cells show digested antigens to T cells through the MHC on their surface, which allows the T cell to “see” the antigen and recognize it as foreign. The connection between the MHC and the receptor on the T cell is the first signal necessary to activate the T cell to respond to a tumor and destroy it.

Explanation:

cancer   is   essentially   uncontrolled   mitosis   of specialized cells

which

what is a measurement of the earth’s history divided into time periods?

> fossil record <

sedimentary rock

> geologic time scale <

radioactive elements