Moreover, in agreement with our previous data indicating that SuFu ubiquitylation correlates with the activity of the Hh signalling pathway (Fig. 4), the formation of the SuFu/Itch/β-arrestin2 complex increased as the pathway is progressively switched off, as shown in postnatal mouse cerebellum tissues (Fig. 5h), and was significantly reduced when the pathway was either activated in response to SAG treatment (Fig. 5i, j) or in MB tumour cells in which the Hh pathway is hyperactivated by deletion of Ptch repressor46 (Fig. 5k). The gene discussed is SAG; the disease is neoplasm.