Szczerba et al. also showed that CTCs from CTC–WBC clusters were predisposed to be exuberant in positive regulators of cell cycle and deoxyribonucleic acid (DNA) replication programs compared to CTCs alone and could express genes that encode granulocyte colony-stimulating factor (G-CSF), which facilitated pro-tumor activities like neutrophil recruitment, Bv8 expression and angiogenesis [29–31]. This evidence concerns the gene PROK2 and neoplasm.