Glioma cell invasion correlates positively with RelB expression. Equal numbers of glioma cells from indicated cell lines were seeded on 3-D collagen matrices and allowed to invade for 48 h, fixed with 3% glutaraldehyde, and stained with 0.1% toluidine blue. (A) Side-view light microscopy images were taken from thin slices of the collagen matrices at 10x magnification. White arrowheads indicate cell monolayer. Scale bars = 100 μm. (B) Quantification of invasion density for cell lines in Figure 1A. Data represent average numbers of invading cells per 1-mm2 field (n = 3 wells) ± S.E.M. (C) Western blot of whole-cell lysates from glioma lines using the indicated antibodies.