PDCD1 and colorectal carcinoma: Considering the above results, we investigated the role of SIGLEC1 in the immunotherapy of patients with CRC and found a positive correlation between SIGLEC1 and LAG3, CD38, PDCD1, KLRD1, TNFRSF4, FCRL4, CD200, and LGALS9 (Figure S2A), indicating that the patients with low SIGLEC1 expression might exhibit weaker anti-tumor immunity.