As TIMP-1 could function as suppressor for MMP2 and MMP9 [24,25], TIMP-1 to MMP2/MMP9 signals may be the key factor to reduce the parental PCa cells invasion treated with the CM from PCa siTR4/THP-1 siTR4 co-culture system. The gene discussed is MMP9; the disease is posterior cortical atrophy.