Fig. 2
From: CHEK2 mutations and papillary thyroid cancer: correlation or coincidence?
Simplified ATM-CHEK2-BRCA1 pathway. In the presence of double strand DNA breaks, sensor protein complexes activate ATM. ATM leads to phosphorylation of CHEK2 and p53 stabilization. CHEK2 also phosphorylates p53 and several other proteins contributing to p53 dependent cell cycle arrest, which lead to apoptosis. CHEK2 activates BRCA1 and other regulators by phosphorylation, leading to the formation of homologous recombination repair complexes. Image courtesy of author