2.4 Apoptotic cell analysis
To demonstrate whether IL-28B directly promotes tumor cell apoptosis, MC38 and RM-1 cells were cultured. When tumor cells are in logarithmic growth, they were paved to 12-well plates (3×105cells/mL) and treated with phosphate-buffered saline (PBS) or IL-28B (100, 200, and 400 ng/mL) for 48 h and 72 h. Cells were stained with an apoptosis kit (KeyGen Biotech, Nanjing, China) according to the manufacturer’s protocol and detected using flow cytometry.