PKP1 and neoplasm: Tumor-infiltrating lymphocyte-B cells (TIL-Bs) produce IgG to tumor antigens such as PKP1 to assist dendritic cell internalization of tumor antigens, which subsequently activates T cells in response to tumor cells; alternatively, HPV-specific IgG may be generated to enhance antigen cross-presentation or provoke and maintain the HPV-specific T-cell reaction.