Figure 1

MRM images that show the MTS growth over time from different angles. The images to the left depict the axial view, whereas those to the right show an arbitrary angle. These 2D images confirm the surface heterogeneity that emerges already 12 hrs post placement of the MTS into the gel, and depict a small group of invasive cells (images on the right) that can also be seen in Figures 2(A) and 3. On the other hand, images on the left demonstrate that certain parts of the solid spheroid actually grew into the gel (red circle).