In: Biology
One of the hallmark of cancer cells is that they are insensitive to antigrowth signals.
The normal cell cycle comprises of a series of tightly regulated events that evntually leads to the generation of two proper daughter cells. At each step of the cell cycle, there are quality control mechanisms which ensure the fidelity of the cell cycle progression. These mechanisms are known as cell cycle check points. For example, S-phase check point ensures that cell cycle progression is halted when it detects damaged DNA/incompletely replicated DNA.
Many proteins are involved in these regulatory processes. One such key protein is Retinoblastoma. It is activated by phosphorylation and inactivated in the unphosphorylated form. Antigrowth signals form the surrounding microenvironment regulate the activity of RB. Cancer cells evolve a myriad of methods to avoid these anti-growth signals. Loss of function mutations in the Rb pathway promotes unregulated cell proliferation. Hence such cancer cells become insensitive to antigrowth signals.