**Figure 6. **POU4 factors modulate the *RIT2* promoter. A firefly luciferase construct containing a fragment *RIT2* –1290 to +76 bp (labeled as –1290) or –374 to +76 bp (–374) was cotransfected into SK-N-AS cells with pcDNA3.1 expression
vectors containing cDNA of the indicated transcription factors, together with pRL-CMV containing the *Renilla* luciferase gene for normalization. Expression vectors tested were for POU4 factor (labeled as POU4F1-s, POU4F1-l, POU4F2-s,
POU4F2-l, and POU4F3 on the x-axis), ISL1, or no insert as control (labeled as pcDNA). Relative luciferase activity was calculated
as the ratio of the normalized luciferase activity with POU4 and/or ISL1 expression vectors to that with empty pcDNA3.1. The
values represent the mean and SEM (error bar). Statistical significance: * p<0.05, ** p<0.001, *** p<0.0001.