This is interesting since it contradicts an early study showing that TR4 could promote prostate cancer metastasis through the tissue inhibitor of metalloproteinase 1 (TIMP-1)/matrix metalloproteinase 2 (MMP2)/MMP9 [23] and C-C chemokine motif ligand 2 (CCL2)/C-C chemokine motif receptor 2 (CCR2) signaling pathways [24]. The gene discussed is MMP2; the disease is prostate carcinoma.