MMP12 and infection: However, M.F. infection increased MMP-12 mRNA by 41.2-fold at 18 hours and 46-fold at 24 hours [Figure 2B].Similar to U937, macrophages showed an increase in MMP-12 secretion with a peak at 72 hours following M.F. infection (about 27 ng/ml), compared to control (about 0.76 ng/ml measured in untreated control and 0.9 ng/ml 243 media treated) [Figure 2C].Moreover, MMP-12 mRNA was increased in M.F. infected macrophages with a 6.3-fold peak after 18 hours of infection, versus 0.59-fold increase in the corresponding control.