Since it has been previously implicated that the expression of a single copy of dnTGFβRII transgene does not completely block TGFβ signaling in T cells, we reasoned that a second copy of dnTGFβRII transgene in homozygous mice further suppresses the downstream signaling, resulting in the development of T cell lymphoma. This evidence concerns the gene TGFB1 and T-cell non-Hodgkin lymphoma.