P-selectin mRNA is diminished in HUVECs from preterm cords. P-selectin mRNA was quantitated in each sample with an RNAse protection assay (see Materials and Methods) and normalized to GAPDH mRNA in the same sample. The ratio of the relative intensities of P-selectin mRNA compared with GAPDH mRNA is shown in the bar graph with the corresponding lane below. The combined relative densitometric units in the term infants was 4.6× greater than in the preterm infants (P = .016).