Fig. 2.

Analysis of MMP-2 expression in the olfactory bulb following olfactory nerve transection injury in MMP-9 KO mice. (a) Representative Western blot illustrating changes in MMP-2 expression at different time points following injury. Lane 1 shows pro and active forms of purified murine MMP-2 standard. Lane 2 shows that MMP-2 is barely detectable in control mice (CTRL). Cyclophilin A (CPA) expression at each time point was used to adjust for differences in protein loading. (b) Plot of the relative amounts of MMP-2 (pro and active forms included in the quantification) from four separate experiments expressed as percentages of CPA. Each experiment represents data from nine separate mice. MMP-2 levels initially increased slowly, rose rapidly after day 3 to a maximum at day 7. MMP-2 levels declined equally as rapidly from day 7 to day 10 or 15. Elevation in the level of MMP-2 in the absence of MMP-9 (MMP-9 KO mice) illustrates that MMP-9 is not required for the increase in MMP-2 expression following olfactory nerve injury. KO, Knockout; MMP, matrix metaloproteinases.