In these studies, we sought to address this question by two means: (1) by assessing the effect of a SYK inhibitor (BI 1002494) on proliferation and invasiveness markers in normal mammary epithelial cells and a number of breast cancer cell lines including long-term treatment of naïve adult mice, and (2) reviewing the Cancer Genome Atlas (TCGA) [21] database to compare genetic characteristics of SYK and the well-known tumour suppressors TP53 and PTEN in samples from invasive breast cancer. This evidence concerns the gene PTEN and invasive breast carcinoma.