Cell Cycle Question 4

A new mutation that arose in one copy of gene X in a somatic cell resulted in the formation of a tumor. Which of the following pieces of evidence best describes how the new mutation directly caused the tumor?

Protein X normally stimulates cell division, and the mutation created an overactive version of protein X.

Protein X normally activates a growth hormone receptor, and the mutation decreased the stability of protein X.

Protein X normally prevents passage through the cell cycle, and the mutation created an overactive version of protein X.

Protein X normally regulates gene expression, and the mutation created an underactive version of protein X that blocked the cell cycle.