Increased expression in human astrocytomas of a 100 kDa protein with sequence homology to the ros tyrosine kinase domain.

A monoclonal antibody against the v-ros synthetic peptide VWETLTLGQQPYPGLSN IEVL (amino acid residues 455-475 of v-ros), which is in the conserved region of the c-ros tyrosine kinase domain, was used for Western blotting of human astrocytoma specimens. High levels of a 100 kDa protein were detected in many of these primary brain tumours. In contrast, low levels of this 100 kDa protein were consistently found in the nontumour brain control samples. This 100 kDa protein is, however, probably not the c-ros protein, but may be a novel cytosolic protein-tyrosine kinase and a marker for early transformation of astrocytomas.