PDCD1 and neoplasm: The latest research also found that readers, mainly YTHDF1, YTHDF2, and YTHDC2, correlated positively with expression levels of several immune checkpoint receptors (including PD-1, T cell immunoglobulin and mucin-domain containing-3, and cytotoxic T-lymphocyte-associated antigen 4) as well as with the abundance of tumor-infiltrating lymphocytes (such as CD8+ T cells, CD4+ T cells, macrophages, and DCs) in several cancers, such as lower-grade glioma (LGG), NSCLC, KIRC and BC (Table 1) [92–99].