KLRK1 and cancer: NKG2D is capable of recognizing stress-induced self-ligands (“induced self”), which are not present or expressed at low levels on healthy cells, but are upregulated on distressed or cancerous cells [29], such as MHC class I polypeptide-related sequence A/B (MICA/MICB) and UL16 binding protein 1-6 (ULBP1-6) in humans, and has been shown to mediate in cancer killing.