NPM1 and cancer: Previous studies on the molecular and cellular events leading to apoptosis in CIGB-300-treated cancer cells showed that CIGB-300 is transported from the cytoplasm to the nucleus and when the CIGB-300 reaches the nucleolus, it inhibits the CK2-mediated phosphorylation of the multifunctional nucleolar protein B23/nucleophosmin (NPM) inducing a nucleolar disassembly leading to apoptosis10,17.