CD4 and neoplasm: Inhibition of GPX4 by RSL3 significantly increased cancer cell ferroptosis, promoted the translocation of CRT to the cell surface, downregulated myeloid-derived suppressor cells and M2-like macrophages, increased the number of CD4+ T cells and CD8+ T cells, improved the immunosuppressive microenvironment of head and neck squamous cell carcinoma (HNSCC), and inhibited tumor progression (67).