GDF15 and neoplasm: Moreover, the interactions between ANGPTL7 and M2 macrophages, ANGPTL7 and monocytes, GDF15 and M1 macrophages, LINC00472 and M2 macrophages, RRM2 and M1 macrophages, RRM2 and monocytes, and SLC2A1 and M1 macrophages were statistically significant in the co-expression analysis between tumor-infiltrating immune cells and ferroptosis-related genes.