PTGER4 and leiomyoma: In this exploratory study, we tested the hypotheses that (1) sarcomas overexpress EP4 relative to normal myometrium, and tumors with aggressive behavior (i.e., LMS) express higher levels of class III β-tubulin and EP4 than those with indeterminate (i.e., STUMP, leiomyomatosis) or benign (i.e., leiomyoma, normal myometrium) behavior; thus, EP4 inhibition may represent a novel targeted therapy for LMS; and (2) expression of class III β-tubulin correlates with resistance to taxanes and poor clinical outcome.