Inhibitory effect of PP on mammosphere formation.

<p>(A, B) Primary mammosphere formation. SUM-149 (A) and SUM-159 (B) cells were incubated with indicated doses of PP or DMSO in mammosphere formation media for 7 days. PP treatment reduced the number of primary mammospheres in a dose-dependent manner. (C, D) Secondary mammosphere formation. SUM-149 (C) and SUM-159 (D) cells were grown in mammosphere formation media and treated with indicated doses of PP for 4 days. Then primary spheres were trypsinized and seeded as secondary mammospheres. [Add sentence summarizing effect of PP.] The results shown are representative of three independent experiments.