At this stage, HEATR1 knockdown in control type II NSC lineages has no impact on proliferation but, strikingly, in brat-deficient tumour cells it prevents overgrowth onset, with proliferation levels per brain lobe detected similar to those in controls (Fig. 2L–P; see Appendix Fig. S1B for mitotic indexes). The gene discussed is HEATR1; the disease is neoplasm.