The invention provides an isolated polypeptide containing the amino acid sequence of SEQ ID NO: 17, 18, 19, 20, 21, 22, 23, 24, or 25. The invention also provides an isolated polypeptide containing an amino acid sequence having at least 50% amino acid identity with SEQ ID NO: 14 and an amino acid sequence of SEQ ID NO: 17, 18, 19, 20, 21, 22, 23, 24, or 25, or a conservative variant thereof. The invention further provides an isolated polypeptide containing the amino acid sequence of SEQ ID NO: 2, 4, 6, 8, 10, or 12. The invention also provides a method for identifying a compound that modulates a FP receptor variant by contacting an isolated FP receptor variant or a FP receptor variant over-expressed in a genetically engineered cell with a compound and determining the level of an indicator which correlates with modulation of a FP receptor variant, where an alteration in the level of the indicator as compared to a control level indicates that the compound is a compound that modulates the FP receptor variant.