SIGLEC15 and cancer: We next examined the associations of TLR4 expression with 8 immune checkpoints (PD-L1, CTLA4, HAVCR2, LAG3, PDCD1, PDCD1LG2, SIGLEC15, and TIGIT), and TLR4 expression was widely associated with the 8 immune checkpoints in most cancer types (Figure 7F).