MYCN and neuroblastoma: First, to assess the PLK1 expression in NB cells, we used MYCN amplified (NGP, KELLY, SK-N-BE(2), NGP and KP-N-NS) and non-amplified (SH-SY5Y, SK-N-SH and NBL-S) NB cell lines for real-time and Western blotting (Figure 1A&B).