CACYBP and neuroblastoma: Since the theoretical analysis indicated that several lysine residues in the amino acid sequence of CacyBP/SIP might be modified by the SUMO moiety, in this work, using different techniques, we checked the hypothesis that this protein might be sumoylated in neuroblastoma NB2a cells and then we identified the sumoylated amino acid residue in CacyBP/SIP.