SLAMF1 and neoplasm: Myeloid immune checkpoint molecules, such as CD47, the signaling lymphocytic activation molecule (SLAM) family, the sialic acid-binding immunoglobulin-type lectin (Siglec) family, and the leukocyte immunoglobulin-like receptor B (LILRB) family [33,34], help mediate inhibitory signals that promote the pro-tumor immune activities of TAMs.