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Figure 1. Mechanisms of NK cells on cell recognition. NK cell cytotoxicity is controlled by the balance of signals from activating and inhibitory receptors. Activating receptors recognize stress- or tumor-specific ligands on target cells, triggering the release of cytotoxic granules (perforin and granzymes). Inhibitory receptors engage with MHC class I molecules on healthy cells, delivering signals that prevent NK cell activation and thus protecting normal tissue from immune attack. Additionally, NK cells mediate ADCC by recognizing antibody-coated target cells via their CD16 receptor, which binds to the Fc portion of IgG antibodies, leading to potent activation and killing of the target cell. Created in BioRender. Tong, C. (2025) https://BioRender.com/hcqmq9n. NK: Natural killer; MHC: major histocompatibility complex; ADCC: antibody-dependent cellular cytotoxicity; CD16: cluster of differentiation 16; Fc: fragment crystallizable region; IgG: immunoglobulin G.