TEK and central nervous system cancer: The levels of expression of the most significant gelatinase enzymes in gliomas, matrix metalloproteinases 9 and 2 (MMP9 and MMP2) [33], were also greater in the conditioned medium of CD14+Tie2+ cells than that of CD14+Tie2- cells (Figure 4C; P < 0.001 for each), although the MMP2 levels were in the low range of detection.