A gene that encodes for a leukemia‐associated phosphoprotein (p18) maps to chromosome bands 1p35–36.1

The cytosolic protein p18 which is expressed in increased amounts in acute leukemia cells is variably phosphorylated as a function of growth and differentiation. Proteins with identical amino acid sequence were independently found to be highly expressed in normal brain tissue and neuroendocrine tumor cells. Here we describe the mapping of the recently cloned p18 gene to chromosome 1, band p35–36.1 by Southern blot analysis of human–rodent somatic cell hybrid DNA and by chromosome in situ hybridization using a p18 genomic probe. This region of the distal short arm of chromosome 1 is a frequent site of deletions or loss of heterozygosity in tumors derived from neural crest cells, particularly neuroblastomas and melanomas. The high levels of expression of p18 in brain and neuroendocrine tumor cells, its possible role in growth regulation, and its chromosomal location in a region frequently deleted in neuroectodermal tumors suggest that this gene may be involved in common genetic events occurring in these tumors.