PRF1 and neoplasm: Perforin and LAMP-1 are two membrane proteins used as surrogate markers of CD8+ T cells' cytotoxic activity.23 Thus CD8+/perforin+ and CD8+/LAMP-1+ double-positive cells, detected by immunofluorescence on CRC specimens, were higher in low miR-27a-expressing tumours (Figures 7A and B).