CXCL12 and prostate carcinoma: The expression of Gpx1 is also regulated by p53,34 and the ablation or mutation of p53 in stromal fibroblasts increased growth and metastatic spread of PC3 prostate cancer cells because of increased production of SDF-1.35 Although the redox status of p53-deficient fibroblasts is unknown, it is conceivable that elevated H2O2 may contribute to their pro-tumorigenic effect.