The expression of Ki67, which is a known cell proliferation marker similar to Psf3, was reported to be higher in the Psf3 high expression group than in the Psf3 low expression group.8, 23, 24 However, upon comparison following immunostaining, Psf3 was mainly detected in the nuclei of tumor cells, whereas ki‐67 was found in both the nuclei and stroma of the tumor cells.23 These results suggested that immunostaining of Psf3 was useful for selectively detecting tumor‐proliferating cells. The gene discussed is MKI67; the disease is neoplasm.