The methods of the present invention, relate to the surprising determination that the level of phosphorylation of position 406 (e.g., a serine residue) of human eukaryotic initiation factor 4B (eIF4B), or a corresponding phosphorylatable amino acid of an ortholog thereof, serves as a biomarker for MELK enzymatic (e.g., kinase) and/or oncogenic activity. The methods of the present invention further relate to the surprising determination that the level of phosphorylation of position 3 (e.g., a threonine residue) and/or position 10 (e.g., a serine residue) and/or position 11 (e.g., a threonine residue) of human Histone M3, or a corresponding phosphorylatable amino acid of an ortholog thereof, also serves as a biomarker for MELK enzymatic (e.g., kinase) and/or oncogenic activity.