TGFB1 and neoplasm: Finally, since the tumor growth dynamics (Fig. 1A–D) are consistent with the predicted level of tumor progression or inhibition in the spleen (Figs 4 and 6), it can be hypothesized that the elevated levels of TGFβ1 found in the adolescent irradiated tumor tissue [10] and in the adolescent irradiated spleen (Fig. 7) is due to communication occurring between these tissues (Fig. 8).