Axon genesis deficiency in Nurr1 deficient SH-SY5Y cell line. A. SH-SY5Y cells were respectively transfected with pSUPER-random and pSUPER-Nurr1 siRNA plasmids. After selection by neomycin, stably transfected cell lines with GFP fluorescence were picked on an inverted fluorescence microscope. B. The clones with decreased NURR1 expression level were identified by Western blot analysis. TOP IIβ protein level was also analyzed in Nurr1 deficient cell line. C. The average neurite length (total neurite length/cell number) was determined from more than 100 cells. Bars represent the mean ± SEM (n = 3 independent experiments). Neurite outgrowth in the pSUPER-random and pSUPER-Nurr1 siRNA plasmids transfected cell lines showed significant difference. **P <0.01 vs. random control.