Credit: Schmidt et al., 2018
Human colon cancer cells injected into mice form tumors (left) consisting of both MAPK-active cells (green) and NOTCH-active cells (red). Treatment with the MAPK inhibitor selumetinib results in tumors consisting of NOTCH-active cells only (center), but after treatment is stopped, the NOTCH-active cells give rise to new MAPK-active cells, restoring the tumors’ original composition (right).