upon stimulation with a phorbol ester and known tumour promoter , 12-o-tetradecanoylphorbol-13-acetate ( tpa ) , the human erythroleukemia k562 cell line , a standard target for human natural killer ( nk ) cells , shows a significant reduction in expression of transferrin receptors ( tfr ) and becomes resistant to nk-mediated cytolysis .
C0031586
phorbol ester
C0039654
12-o-tetradecanoylphorbol-13-acetate