Although multiple groups have identified PD-1 on diverse cancer cell types, including B16-F105,7,12,15,16, one study surprisingly claims that B16-F10 cells are negative for PD-1, and that PD-1 ab clones, such as 29F.1A12, exclusively bind to an off-target nuclear antigen exposed by dead cells34. This evidence concerns the gene PDCD1 and cancer.