BRCA1 and cancer: BRCA1 (breast cancer 1), one of the key players in the cell cycle checkpoint and homologous recombination (HR), interacts with the mRNA splicing factor BCLAF1. This BRCA1-BCLAF1 complex regulates mRNA splicing of DDR genes ATRIP, BACH1, and EXO1 in response to DNA damage, although AS of these genes were not detected in this study.