We also saw a partial effect of the control SSO on tumour growth (Fig. 4a, b, d), suggesting a mild toxic or off-target effect, potentially due to the guanidinium mini-dendrimer present in the vivo-morpholinos; however, overall both SSOs appeared well tolerated by the mice (Fig. 4c), which was as expected, since we confirmed minimal complementarity between the mouse ERG gene and our E43′ SSO (Supplementary Fig. 3a). The gene discussed is ERG; the disease is neoplasm.