SMAD3 and neoplasm: However, the use of anti-NK1.1 antibody may also deplete NKT cells; therefore, the specific role of Smad3 in NK cell production was further examined by adoptive transfer of Smad3−/− or Smad3+/+ NK cells (NK1.1+) into the tumour-bearing NK cell deficiency mice (NOD/SCID).