Moreover, like the Killer-of-prune mutation in Drosophila NDK and the neuroblastomaSer120 --> Gly mutation in human NDK-A/Nm23-H1, the Ser122 --> Pro substitution in NDK-B affects the stability of the protein toward heat and urea.
A similar ser120-gly mutation in NME1 has been found in human neuroblastoma, suggesting that mutation in this region may be a general phenomenon related to tumor progression.