To determine whether IGF-I affects early tumor development, brains from asymptomatic Ptc1+/+, Ptc1+/+/IGF-I Tg, Ptc1+/- and Ptc1+/-/IGF-I Tg mice at 3, 5 or 8 weeks were histologically examined and cerebellar pathology was assessed (Figure 5B). The gene discussed is IGF1; the disease is neoplasm.