The only other gene in the 86-gene drug resistance array that was up-regulated in Rh30VR, Rh41VR, and TC71VR cells was the known direct GLI1 target and multidrug resistance gene, MDR1. Only one gene was down-regulated in Rh30VR, Rh41VR, and TC71VR cells, the receptor tyrosine kinase, ERBB3. ERBB3, a member of the epidermal growth factor receptor family, is often aberrantly expressed and/or activated in cancers and has been associated with drug resistance [47]. This evidence concerns the gene NTRK1 and cancer.