Natural killer (NK) cells play a crucial role in cancer immunosurveillance. Circulating NK cells can kill target cells without prior sensitization. There are some receptors known to impact the activity of NK cells, such as the inhibitory NK cell receptor TIM3, among others, which recognizes phosphatidylserine on the surface of cells. More research has been performed using targeted or genome-wide CRISPR screening to identify cancer cell genes that impact NK cell-killing ability.