MMP14 and prostate cancer: Prostate cancer CTCs form invadopodium projections, which are enriched with endosome-regulated proteins such as the metalloproteinase MT1-MMP and tyrosine kinase substrate 5 (Tks5), and they can utilise these to proteolytically modify the endothelium and gain access to distant sites (Figure 6) [152,153,154,155].