These data collectively suggest: (1) the basic DNA-binding domain of Meq plays an important role in MDV transformation (tumor incidence); (2) the transcriptional regulatory domain of Meq influences the distribution and size of MDV-induced tumors; and (3) a combination of sequences in the Meq basic DNA-binding domain from Md5 and the transcriptional regulatory domain from CVI988/Rispens results in the development of large and widely distributed visceral tumors using rMd5 as the genetic background. This evidence concerns the gene RMND5A and neoplasm.