PRRX1 and breast carcinoma: Importantly, the nuclear proportion of SIRT1 and PRRX1 are significantly correlated with each other, i.e., more than 90% metastases were nuclear SIRT1-PRRX1 double negative/low (Fig. 7g, P<0.001), supporting a SIRT1-PRRX1 axis in regulating breast cancer metastasis.