Mechanistically, GLP promoted the differentiation of myeloid-derived suppressor cells (MDSCs) and inhibited MDSC accumulation in spleen and tumor tissues through the caspase recruitment domain-containing protein 9 (CARD9)/nuclear factor-κB (NF-κB)/indoleamine 2,3-dioxygenase (IDO) signaling pathway. Here, CARD9 is linked to neoplasm.