In a subsequent study, uveal melanoma cell lines that were resistant to NK cell lysis were shown to have a high constitutive expression of MHC class I. When these cell lines were incubated in TGF-β (a down regulator of MHC class I on normal cells), significant reduction in MHC class I expression was noted as well as a corresponding increase in susceptibility to NK cell lysis [52]. The gene discussed is TGFB1; the disease is uveal melanoma.