2015). PCNA and BrdU are often overexpressed in tumour cells and commonly used as markers of cell proliferation. PCNA is the proliferative-associated protein controlling cell growth (Bravo et al. 1987). BrdU, a thymidine analog, readily incorporates into proliferating cells (Kee et al. 2002). Injection of BrdU into mice for 3 h before sacrifice allows incorporation into intestinal DNA in place of thymidine. A combination with anti-BrdU for IHC analysis indicates the status of cell proliferation in situ. Here, PCNA is linked to neoplasm.