UCP3 and neoplasm: To test whether UCP3 confers resistance to tumorigenesis mainly through effects on tumour initiation or tumour promotion, and to test the effect of UCP3 overexpression on tumour formation in a genetic model, we crossed K5-UCP3 animals with ‘pre-initiated' Tg.AC mice, which harbour an oncogenic v-Ha-Ras transgene19.