Knock-down of transcription factors Sp1/Sp4 decrease endogenous TRPV1 mRNA in cultured DRG neurons. (A) Evidence of Sp1mRNA knockdown following transfection of siSp1 in cultured DRG neurons (***) p < 0.0001 (left). Apparent changes in Sp4 (middle) or TRPV1 mRNA (right) were not significant (ns). (B) Transfection of siSp4 resulted in an apparent knockdown of Sp1, Sp4 and TRPV1 mRNA. Combined knockdown of Sp1 + Sp4 using an equal ratio (1:1) of siSp1/siSp4 resulted in the most consistent knockdown of endogenous TRPV1 mRNA. Error bars SEM (n = 3) triplicates measures. Two tailed unpaired t-test. Significant differences: (*) p < 0.05; (***) p < 0.0001. RQ values of siRNA treated DRGs are compared relative to the RQ values of scrambled controls which represent baseline amounts of Sp1, Sp4 or TRPV1 mRNA following transfection of a scrambled siRNA or Spx control vector, see Methods for details.