Nevertheless, we also found that the strongly enhanced ISR via GADD34 homozygous mutation significantly increased pre-malignant GCP apoptosis in hyperplastic lesions and reduced the lesion numbers in young Ptch1+/− mice, resulting in the significant reduction of medulloblastoma incidence in adult Ptch1+/− mice. The gene discussed is PTCH1; the disease is medulloblastoma.