MKI67 and neoplasm: Subcutaneous transplantation of HCC827 stable clones into BALB/c-nu/nu mice demonstrated that tumor growth was markedly suppressed in mice transplanted with α5-nAChR-knockdown cells compared to that in mice transplanted with control cells (Figure 5C); compared with HCC827-shα5 tumors, the HCC827-SC tumors have a higher α5-nAChR expression (α5-nAChR) and proliferation index (Ki67) demonstrated by immunohistochemistry (Figure 5D).