Additionally, two known potential BC markers, NUMA1 (nuclear mitotic apparatus protein 1) and CFHR1 (complement factor H related 1), and two housekeeping genes, ACTB (β-actin) and TUBB (tubulin-β), reported in previous studies [8, 29–32], were also included as controls for evaluation of the MRM-MS assay. This evidence concerns the gene ACTB and breast cancer.