PFKFB4 and melanoma: Because during Xenopus laevis embryonic development, the migration of melanocytes and melanoma progenitors, the neural crest cells, is also controlled by PFKFB4 (35), we postulated that human and frog protein functions were conserved, allowing us to devise phenotype rescue experiments: Frog pfkfb4 encodes a protein with 95% similarity with the human protein, but the mRNA was not targeted by siRNAs designed against the human mRNA sequence.