Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Although Hh signaling by SMOH was reported to be required in a chronic myeloid leukemia-like disease (Dierks et al., 2008; Zhao et al., 2009), it was found to be dispensable for the development of acute leukemias induced by either the Received 3 November 2009; revised 20 April 2010; accepted 20 May 2010; published online 5 July 2010 Correspondence: Dr TN Hartmann or Professor R Greil, Laboratory for Immunological and Molecular Cancer Research, IIIrd Medical Department with Hematology, Medical Oncology, Hemostaseology, Rheumatology and Infectiology, Paracelsus Medical University, Salzburg 5020, Austria.
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