FAKsiRNA significantly decreased FAK and caused MCF-7 cell rounding and decreased cell growth in vitro and tumorigenesis in vivo. A, Western blotting demonstrates that FAKsiRNA#1 and FAKsiRNA #2 decreased expression of FAK in MCF-7 cells, while Control siRNA and Vector control samples did not affect FAK expression. B, FAKsiRNA causes increased cell rounding. GFP-positive MCF-7, MCF-7-Vector, MCF-7-Control siRNA and FAKsiRNA#1 and #2 cell lines with rounded morphology (shown on right panels) were counted on three separate fields with 100 cells counted per field. The average percent of rounding is shown ± standard errors. *, p < 0.05, FAKsiRNA versus control samples. C, FAKsiRNA caused decreased cell growth in vitro. MCF-7, MCF-7-Vector, MCF-7-Control (luciferase) siRNA and FAKsiRNA#1 and #2 cells were plated on a 6-well plate, cultivated for 1, 4, 6 and 8 days were and counted on hemocytometer with trypan blue for detection of viable cell growth. FAKsiRNA#1 and #2 significantly decreased cell growth compared to control MCF-7, MCF-7-Vector or Control siRNA cells. *, p < 0.05 FAKsiRNA#1 and FAKsiRNA#2 versus control cells.