ATR and Fanconi anemia: Recent research has demonstrated that blocking checkpoint kinases can lead to synthetic lethality when combined with the inhibition of factors from the same pathway (ATR, CHK1, WEE1) or the chromatin assembly and DNA repair pathways (TLKs, BRCA2, PARP1, ERCC1-XPF, Fanconi anemia, p53) (21, 48).