Analysis of GTSF1 mRNA expression levels in human liver cancer cell lines following transfection with two siRNA molecules targeting GTSF1. (A) Silencing of relative GTSF1 mRNA expression in PLC/PRF/5 cell lines using siRNA1 and siRNA2. Error bars denote the standard deviation, and calculated **P<0.01 compared with siNC. (B) Silencing of relative GTSF1 mRNA expression in Huh-7 cell lines using siRNA1 and siRNA2. (C) The relative cellular proliferation level of GTSF1-siNC-, GTSF1-siRNA1- and GTSF1-siRNA2-transfected PLC/PRF/5 cells from days 1–6. The level of relative proliferation was measured at 450 nm absorbance after 1 h of incubation. The relative proliferation of PLC/PRF/5 cells was significantly decreased from days 3–6, when compared with the GTSF1-siNC and siRNA groups. Cell growth assays were performed in 96-well microtiter plates and all assays were performed in triplicate. GTSF1 expression without siRNA interference (GTSF1-siNC) was used as the positive control. (D) The relative cellular proliferation level of Huh-7 cells following GTSF1-siNC, GTSF1-siRNA1 and GTSF1-siRNA2 interference. **P<0.01 (relative GTSF1 mRNA expression in GTSF1-siNC groups compared with GTSF1-siRNA1 groups and in GTSF1-siNC groups compared with GTSF1-siRNA2 groups). *P<0.05 (relative proliferation in GTSF1-siRNA1 and GTSF1-siRNA2 groups compared with the GTSF1-siNC group). NC, negative control; GTSF1, gametocyte specific factor 1; si, small interfering.