Biomarker analysis of Fraction-1 from unexposed pregnant women. Duplicate serum samples from two unexposed pregnant women (G1 and G2) from the control group were separated on HPLC, followed by E-Screen analysis of the reconstituted Fr-1 (0–5.5 minutes). Fr-1 was analyzed in the presence or absence of ICI as indicated. Results are expressed as the relative proliferative effect (RPE) to E2. Values shown are mean ± SD from triplicate wells.