SMO and breast cancer: Other studies have reported that pharmacological inhibition of SMO at doses of 10 μM or higher [10,48] inhibit the growth of a subset of breast cancer cell lines in vitro; however, the high doses required to affect tumor cell growth, as compared to those needed for the inhibition of the pathway in the stroma, suggests that the observed growth inhibition is due to off-target effects or inhibition of non-canonical Hh signaling.