Resistance to therapy is a major problem in advanced cancers, and new therapeutic approaches are needed. Here, we propose a novel target and approaches for its targeting. We will explore the hypothesis that STIL (SCL TAL I Interrupting Locus, previously known as STIL NP_003026.1) is a novel and effective target for therapy in ovarian and breast cancers, and that drugs identified through connectivity map analysis (C-MAP) of cancer cells treated with siRNA against STIL could enhance the activity of systemic siRNA therapy of STIL. The Centreosomal protein STIL expression in multiple cancers is associated with poor prognosis and metastasis. Silencing STIL by siRNA causes apoptosis of cancer cells at mitotic entry in-vitro and in-vivo as also demonstrated by collaborative preliminary research between SI and AS. The selective activity of STIL siRNA may be explained our recent discoveries of STIL's role in Centreosomal biogenesis, and most relevant to ovarian and breast cancers, by its hypothesized involvement in the BRCA pathway of DNA repair.