Figure 2: Effect of overexpression of IL6 and IL6knockdown on cell proliferation, migration, and invasion. The expression of IL6 in HT1376 cells was determined by RT-PCR and ELISA after stable transfection with the IL6 expression vector (a) and in T24 cells after IL6 knockdown treatment (b). Data are expressed as mean (±SE; ) of the IL6 levels. (c) Cell proliferation of mock-transfected HT1376 cells (HT-DNA; black circle) and of IL6-transfected HT1376 cells (HT-IL6, white circle). (d) Cell proliferation of mock-IL6-knockdown T24 cells (T24-GFPsi; black circle) and of IL6-knockdown T24 cells (T24-IL6si, white circle). Cell proliferation was determined using the 3H-thymidine incorporation method. Each point on the curve represents the mean percent ±SE ( ) of -thymidine incorporation on day 1. * indicated a statistically significant difference of cell numbers relative to mock-transfected cells on the same day. Comparisons of the migration (white bars) and invasion (black bars) activities between the HT-DNA and the HT-IL6 cells (e) and between the T24-GFPsi and the T24-IL6si cells (f) were determined by in vitro invasion and migration assays. Experimental data are presented as the mean percentage ±SE ( ) of the absorbance in relation to that of the mock-transfected cell group. * .