The six cell lines included megakaryoblastic leukaemia line UT7/Epo cells (known to be Epo responsive; Laugsch et al, 2008) as a positive control; a renal carcinoma line 769P (with extremely low levels of EpoR mRNA) (Elliott et al, 2006) as a negative control; and four cell lines in which rHuEpo has been reported to induce an in vitro response: breast carcinoma line MCF-7 (Acs et al, 2001), cervical carcinoma line HeLa (Acs et al, 2003; Pajonk et al, 2004), renal carcinoma line CAKI-2 (Westenfelder and Baranowski, 2000), and neuroblastoma line SHSY-5Y (Um et al, 2007). The gene discussed is EPO; the disease is leukemia.