MKI67 and cancer: Ki‐67 is an important proliferation marker that has been widely used as a grading marker for many types of human cancers.[37] Immunofluorescence staining showed that Ki‐67 positive cells were significantly reduced in both the cisplatin alone group and SeCD‐cisplatin co‐treatment group (Figure S9c, Supporting Information), further confirming that SeCD supplementation did not interfere with the chemotherapeutic efficacy of cisplatin.