PDCD1 and colon adenocarcinoma: Tumour models were established by subcutaneous injection of the MC38 colon adenocarcinoma cell line in a homozygous mouse model. Mice were treated with a DC1–DLK1 vaccine in combination with anti-PD-1 antibody to enhance efficacy. Vaccine-induced immune responses and anti-tumour effects were assessed by flow cytometry, immunohistochemistry, immunofluorescence, and quantitative PCR.