Objective To probe matrine acting on natural killer cell(NK)activating receptor NKG2D ligands expression in CML cell line K562 and its underlying molecular mechanism.Methods The expression of NKG2D ligands(major histocompatibility complex class I chain-related molecule A or B(MICA/B),UL16-binding proteins(ULBP)1,2,and 3 on K562 cells were analyzed before and after treated with matrine by FCM.The cytotoxic sensitivity of K562 to NK cell was detected by FCM after Objective To probe matrine acting on natural killer cell (NK) activating receptor NKG2D ligands expression in CML cell line K562 and its underlying molecular mechanism. Methods The expression of NKG2D ligands (major histocompatibility complex class I chain-related molecule A or B (MICA / B), UL16-binding proteins (ULBP) 1, 2, and 3 on K562 cells were analyzed before and after treated with matrine by FCM. The cytotoxic sensitivity of K562 to NK cells was detected by FCM after