Steap mRNA expression in human tissues by quantitative real-time PCR. Quantitative real-time PCR was carried out using human cDNA samples. Products are normalized to β-actin for each tissue and adjusted to a percent of the maximum value obtained for that tissue. (A) Steap1 mRNA expression; (B) Steap2 mRNA expression; (C) Steap4 mRNA expression. Each cDNA sample was amplified 3 times. Error bars represent ± 1 standard deviation (SD).