PCNA and neoplasm: The immunohistochemical staining showed that compared with anti‐PD1 mice, the level of Ki67+, PCNA in anti‐PD1 + SR‐B1−/+ mice were significantly reduced, while the level of CASP3 was significantly increased (p < 0.001), which indicated that SRB1 knockdown combined with anti‐PD1 therapy significantly inhibits the growth of tumor cells.