GZMB and acute myeloid leukemia: For BMMCs after in vitro stimulation, the proportion of apoptotic K562 cells was significantly positively correlated with PFP and GZMB levels of NK cells in AML (r = 0.86, p = 0.027, and r = 0.83, p = 0.042, respectively, Figure 4B,C), and showed a positive correlation trend with PFP levels of NK cells in HDs (r = 0.77, p = 0.13, Figure 4B), but did not show a significant difference with GZMB levels in HDs (p = 0.43, Figure 4C).