MMP1 and breast cancer: Al-Souhibani et al. showed that TTP expression is significantly lower in invasive breast cancer cells compared to normal breast cells, and that the genes involved in cellular growth, invasion, and metastasis, namely matrix metalloproteinase 1 (MMP1), urokinase-type plasminogen activator (uPA), and urokinase plasminogen activator receptor (uPAR), were directly regulated by TTP in breast cancer cells [21].