IGF-1R suppressed neurons remain as multipolar cells even at P4. Cells arrested in the VZ/SVZ/IZ in brains electroporated with the shRNA-IGF-1R and analyzed at P4 are mainly multipolar cells arranged in heterotopic groups (right). Control cells in layers II-IV show normal differentiation with a ramified dendrite (arrowhead) and a trailing axon (left). Calibration bar = 10 μm.