You are studying a drug that leads to cell cycle arrest during mitosis. You examine levels of cyclin and cdk proteins in the cells treated with the drug, and untreated cells as control. Shown below are the Western blot results of protein expression.

The genetic content of each somatic cell in an organism is the same, but not all genes are expressed in every cell. Why can't cells express all the genes they have?

Drug X shown below is a kinase inhibitor used to treat multiple types of breast cancer. Breast cancer cells are treated with the drug and after 8 hr are lysed and the presence of various proteins is shown by a band on a western blot. The presence of the phosphorylated form of the protein is shown by the presence of a band when probed with antibodies that recognize the phosphorylated form of protein and are indicated by a p- in front of protein name (e.g. p-AKT). Based on this information, which kinase is likely the target and is inhibited by Justify your answer in 3-4 sentences. Drug X. F FF N. -N S IZ H₂N `N No Drug (+) Drug p-AKT AKT p-GSK3B GSK3B p-p70S6K p70S6K

Describe how the anaphase-promoting complex (APC) is activated in cells (name the cellular/molecular components involved).