The present invention relates to compositions and methods for treating, characterizing and diagnosing ovarian cancer. In particular, the present invention provides methods for treating and/or preventing ovarian cancer in a subject by administering to the subject an effective amount of Mullerian Inhibiting substance and/or an effective amount of an agent that inhibits BCRP1. The present invention further provides methods to identify and/or enrich for populations of ovarian cancer stem cells and populations of somatic ovarian stem cells, in particular, enrichment for populations of coelomic somatic ovarian stem cells, subcoelomic/stromal somatic ovarian stem cells and periphilar medullary somatic ovarian stem cells. The present invention also provides somatic ovarian stem cell markers and ovarian cancer stem cell markers, as well as methods to identify agents which selectively inhibit the proliferation of ovarian cancer stem cells as compared to somatic ovarian stem cells.
