Activation by phosphatidyl serine (PtdSer) externalized on apoptotic cells complexed with the protein ligands protein S1 (PROS1) or growth arrest specific factor 6 (GAS6) leads to activation of downstream pathways, including PI3K/AKT and MAPK/ERK, and promotes tumor cell survival (27, 28). The gene discussed is PROS1; the disease is neoplasm.