In the meantime, an isoform of SRC3, namely AIB1Δ4 was implicated in the progression of early-stage TNBC: a minor subset of early-stage breast cancer cells expressing AIB1Δ4 enables bulk tumor cells to become invasive, suggesting that selective eradication of this population could impair breast cancer metastasis. This evidence concerns the gene NCOA3 and breast carcinoma.