In vitro invasion assay. Invasiveness of RH30 and RD wt (wild type) cells together with RH30 and RD shRNA (silenced) cells was measured using a modified Boyden chamber assay in the presence of NIH/3T3 cell conditioned medium as chemo-attractant. (A) One of three independent experiments is reported (magnification 400×). (B) The results represent the mean ± standard deviation of quintuplicate samples from three independent experiments. A.U., arbitrary unit. Control corresponds to wild type cells (black bars); shRNA corresponds to HPSE silenced cells (hatched bars). An asterisk (*) indicates a significant difference from control (P < 0.05).