PCNA and neoplasm: Moreover, in subcutaneous xenograft tumour models treated with 5‐fluorouracil, the volumes of subcutaneous xenograft tumour in DCLK1 knock‐down group were significantly smaller compared to the control (Figure 2I‐a–c), and the TUNEL staining of subcutaneous xenograft tumour was increased, while the PCNA staining was decreased (Figure 2I‐d).