Maguire et al. showed that SF3B1 K700E mutations are associated with differential gene splicing in breast cancer, including of TMEM14C, RPL31, CRNDE, DYNLL1, ICA1, RPL24, and MTERFD3. Cell lines carrying the SF3B1 mutation were sensitive to the SF3b complex inhibitor spliceostatin A, which suppressed tumor growth. Here, TMEM14C is linked to breast cancer.