Among these, a copy number variation (CNV), namely the 16q23 gain, encoding v-maf avian musculo-aponeurotic fibro-sarcoma oncogene homolog (MAF) transcription factor, was shown to drive the process of bone colonization in ER-positive BC cell lines; the detection of at least 1.5 copies of this region in 334 paraffin-embedded BC samples, normalized to the CEP16 centromeric probe, significantly correlated with BM occurrence at any time (p < 0.001) [84]. Here, MAF is linked to breast cancer.