In addition to adjacent cells, cell communication also occurs between cells that are not adjacent through direct cell-cell contact; for example, CD24 expressed by tumour cell can interact with the inhibitory receptor sialic-acid-binding Ig-like lectin 10 (Siglec-10), which is expressed by tumour-associated macrophages to send anti-phagocytic signal [21]. Here, CD24 is linked to neoplasm.