SMAD3 and neoplasm: Compared with GFP+ Smad3+/+ chimeric mice, mice with GFP+ Smad3−/− bone marrow exhibited significant reduction in the tumour growth and mortality rate (Fig. 3b,c), which was again associated with a 10-fold increase in GFP+ NK1.1+ cells in the tumour microenvironment (Fig. 3a).