MKI67 and neoplasm: In accordance with the results, no difference in pathological findings was obtained between tumor masses of PSTC‐1‐UPRT‐PC‐9 and PSTC‐1‐Null‐PC‐9, such as invasion of cells with dense nuclear staining and positive for Ki‐67, and rich stroma in tumor tissues (Figure 4C, upper and middle).