NCAM1 and small intestine neoplasm: However, immunohistochemical characterization of small intestinal tumors from PKA antagonist Rp-8-Br-cAMPS treated animals did not reveal any significant changes in the number of CD3+ T cells, CD8+ cytotoxic T cells, Foxp3+ Tregs or CD56+ natural killer (NK) cells (Figure 2A, B and Additional file 2, Figure S1).