ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: These are intriguing results; the lack of difference in expression of the key positive regulator of Hh signalling SMO is in contrast with Dierks et al. who demonstrated that Smo expression was upregulated at the RNA and protein level in murine BCR-ABL+ cells27, providing a possible mechanism for Hh over activity in CML cells.