Indeed, PD-L2 transcript levels were upregulated in TIS in cancer cell lines of several origins, namely, human melanoma (SK-MEL-103), mouse melanoma (B16-F1, B16-F10, HCmel3, HCmel12), mouse pancreatic adenocarcinoma (Panc02), human lung squamous cell carcinoma (H226), human head and neck squamous cell carcinoma (UT-SCC-2, UT-SCC-38, UT-SCC-42B), human pancreatic adenocarcinoma (Panc1), and human osteosarcoma (U2OS) (Fig. 1a–c and Extended Data Fig. 1b–g). Here, PDCD1LG2 is linked to head and neck squamous cell carcinoma.