ESR1 and neoplasm: Both tumor-enriched and tumor-depleted HLA alternative splicing events were common, with 30.6%, 10.7% and 14.7% of LUAD, LUSC and ER+ breast tumors harboring at least one tumor-enriched alternative splicing event and 22.6%, 21.4% and 14.7% of LUAD, LUSC and ER+ tumors harboring at least one tumor-depleted alternative splicing event (Fig. 4a).