NUCLEOLIN and infection: Moreover, ectopic HDGF overexpression by infection with adenovirus vectors encoding HDGF (Ad-HDGF) significantly increased the NCL protein level, whereas HDGF silencing by infection with adenovirus vectors encoding HDGF small interfering RNA (Ad-HDGF RNAi) decreased the NCL protein level in SK-Hep-1 cells (Figure 2F).