Final answer:
Bcl-xL is an anti-apoptotic protein, Bax is a pro-apoptotic protein, and p53 is a transcription factor involved in cell cycle regulation and apoptosis.
Step-by-step explanation:
Bcl-xL, Bax, and p53 are proteins that play important roles in cell cycle regulation and apoptosis (programmed cell death). Bcl-xL is an anti-apoptotic protein that inhibits cell death by preventing the release of cytochrome c from mitochondria. Bax, on the other hand, is a pro-apoptotic protein that promotes cell death by forming pores in the mitochondrial membrane. p53 is a transcription factor that regulates the expression of genes involved in DNA repair and apoptosis. When DNA damage is detected, p53 can halt the cell cycle and initiate repair or trigger apoptosis if the damage is irreparable.