TWIST1 over-expression increased invasiveness of SNB19 cells in vivo. (A) Representative images generated after intracranial injection of GFP-labeled SNB19 Ctrl (left) and SNB19 TW cells (right) show isolated and aggregate cell invasion adjacent to a central tumor core (type 2 growth pattern). Each 3-D confocal image is from a representative individual axial brain slice used for reconstruction of the growth pattern of the total tumor. After imaging and reconstruction, whole brain images were analyzed using Huygens software. The number of invasive aggregates (B), and total volume (VoxVol) of invasive aggregates per tumor (C) were significantly greater in SNB19 TW cells compared with controls (p = 0.0037 and 0.0166, respectively). Arrows demonstrate invasive cell aggregates around central tumor core.