ARID1A and breast neoplasm: Recent examples of novel CGDs discovered through genetic screening approaches include an increased sensitivity of ARID1A mutant cell lines to inhibition of the ARID1A paralog ARID1B (Helming et al., 2014), of PTEN mutant breast tumor cell lines to inhibition of the mitotic checkpoint kinase TTK (Brough et al., 2011b), and of MYC-amplified breast tumor cell lines to inhibition of multiple distinct splicing components (Hsu et al., 2015).