MLLT3 and breast cancer: BLBC is commonly known as TNBC because most cases lack expression of estrogen and progesterone receptors and exhibit the OE and/or amplification of HER2.38 The AF9 mRNA levels decrease sequentially in luminal A, luminal B, Her2-enriched, and BLBC, indicating that AF9 could function as a potential breast cancer suppressor in the clinic.