In the G1 phase there are two types of DNA damage responses, the p53-dependent and the p53-independent pathways. The p53-dependent responses inhibit CDKs through the up-regulation of genes encoding CKIs mediated by the p53 protein, whereas the p53-independent mechanisms inhibit CDKs through the inhibitory T14Y15 phosphorylation of Cdk2. Failure of DNA damage checkpoints in G1 leads to mutagenic replication of damaged templates and other replication defects. Source: Reactome http://www.reactome.org/cgi-bin/eventbrowser?DB=gk_current&FOCUS_SPECIES=Homo%20sapiens&ID=69615& Adapted from http://www.genomeknowledge.org/, and Maeda et al. Journal of Invest Dermatol. 2002. 119:22-26. e5642 Maeda Gadd45 regulates G2/m arrest G1/S DNA damage checkpoint pathway PW:0000095 Pathway Ontology 12164919 PubMed GADD45 regulates G2/M arrest, DNA repair, and cell death in keratinocytes following ultraviolet exposure. J Invest Dermatol 2002 Maeda T Hanna AN Sim AB Chua PP Chong MT Tron VA