SIRPA and neoplasm: We next examined the PD-L1 expression and PI3K/AKT signaling activation in macrophages and G-MDSCs in these tumor tissues, and found that compared with the control group, anti-SIRPα treatment downregulated p-AKT and PD-L1 expression in myeloid cells (Fig. 5H, I and Fig. S3A, B).