PN-1, PAI-1 and uPA mRNA expression in human breast tumor tissues and normal human mammary tissue. RNA was isolated from 26 breast tumors (T1–T26) and 10 normal breast samples. Normal samples were pooled into two equal groups (N1 and N2). mRNA levels for each gene were evaluated by QRT-PCR. Relative levels of PN-1, PAI-1 and uPA mRNA were normalized to TATA binding protein mRNA levels. Comparative CT method was used to calculate fold difference of PN-1 (A), PAI-1 (B) and uPA (C) expression in breast tumor tissue as compared to levels measured in normal breast tissue. The mean value of the two pooled normal samples was calculated and assigned a value of one in order to determine relative fold change of expression within the tumor samples. The standard deviation of the normal samples was 0.263. The box represents one standard deviation of the mean values obtained from normal mammary tissues.