PDCD1 and breast cancer: Additionally, MIR4435-2HG has the potential to enhance the polarization of M1 to M2 macrophages, increase macrophage migration, elevate the expression of programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated antigen-4 (CTLA4), suppress the immune response of CD8+ T cells, and stimulate the growth and migration of breast cancer cells [17].