Also, we noticed that in our initial sphere screening with different melanoma cell lines, SK-MEL-28 cells that harbor mutant p53 (p53R145L mutant)28 and lack of NGFR (Fig. 2a) were unable to form spheres (data not shown), which were dramatically different from the NGFR-containing SK-MEL-147 or SK-MEL103 cells (Figs. 1–3). The gene discussed is NGFR; the disease is melanoma.