p53 (TP53)

What it is. Transcription factor that integrates many cellular stress signals and decides between temporary arrest, DNA repair, senescence, or apoptosis.

Why it matters here. Central decision hub for cell-intrinsic policing; loss-of-function is among the most common changes in human cancers.

Notes. Type: tumor suppressor; Pathways: DNA damage response (ATM/ATR→p53), ARF–MDM2–p53.