Highlighting the potential ‘yin-yang’ nature of alternative splicing, the short isoform of BRD4 (BRD4-S) generated from exon 12–20 skipping was oncogenic in breast cancer cell proliferation and metastasis, whereas the long isoform BRD4-L exhibited tumor suppressor properties [24,25]. This evidence concerns the gene BRD4 and breast carcinoma.