DNA damage checkpoints are crucial for preventing cell proliferation when DNA damage has occurred The role of DNA checkpoint proteins in the cell cycle is closely tied to the roles of DNA repair enzymes, although these proteins perform different functions. Which of the following statements is true for DNA checkpoint proteins and not for DNA repair enzymes? A. These proteins remove a single nucleotide of damaged DNA B. These proteins nick the phosphodiester backbone of the damaged DNA. C. These proteins prevent the cell cycle from progressing if damaged DNA is detected D. These proteins remove the region of damaged DNA.