Fig. 1. p53 helps cells to avoid transcription-replication conflicts and repair their consequences.

A Under normal S phase p53 prevents DNA topological stress that could occur through conflicts between the transcription and replication machineries [55]. B Deregulated transcription may induce topological barriers that interfere with DNA replication resulting in replication stress (RS). DNA breaks can also induce RS. In response to such stress, p53 is activated by ATM/ATR-regulated signaling pathways, resulting in repair, cell cycle arrest or apoptosis.