TGFA and neoplasm: Given the evident upregulation of Tgf-α during the PNET tumorigenesis pathway, we sought to assess its possible functional contribution by crossbreeding the RT2 transgenic mice with waved-1 mutant mice harboring a mutant loss-of-function allele of Tgf-α that is characterized by the near extinction of Tgf-α expression.36,37 We surveyed the key parameters of tumor progression in cohorts of compound RT2: Tgf-α mutant mice of different ages, aiming to identify stages of disease progression that were affected by the loss of Tgf-α function.