GLI2 and Patent ductus arteriosus: Of the 51 PDA tumors characterized as GLI2 high, a relatively even distribution between high purity (>33% tumor/stromal cell content; n = 23) and low purity (<33% tumor/stromal cell content; n = 27) samples was observed (see Materials and methods for details), indicating that GLI2 expression in stromal cells is an unlikely confounding factor in determining tumor cell GLI2 status in this patient cohort.