To identify the optimal Pem concentration for the treatment in the selected cancer cell lines, serial dilutions of Pem (3 nM–1 μM) were used and cell proliferation was evaluated at 24 and 48 h employing MTT assay and analyzing the expression of the nuclear Ki67 factor, a well-known marker of cell proliferation (Additional file 1: Fig. S1A, B). The gene discussed is MKI67; the disease is cancer.