CHL1 and neoplasm: Since surface receptors are strongly involved in tumour invasion and data have indicated that changes in neural cell adhesion molecule (NCAM, CD56) expression play an essential part in the progression of NB, we investigated NCAM expression (Blaheta et al, 2002), and the NCAM regulating proteins N-myc, p73 and deltaNp73 (Blaheta et al, 2004) under the influence of VPA.