Immunohistochemical evidence for preproenkephalin A synthesis in human retinoblastoma

Human retinoblastoma contains clusters of cells immunoreactive for methionine-enkephalin and methionine-enkephalin-arginine-phenylalanine. Some tumour cells also exhibited methionine-enkephalin-arginine-glycine-leucine-like immunoreactivity. The results are in agreement with those obtained with similar testing of neuroblastoma cell cultures. It is concluded that some human retinoblastoma cells are capable of synthesizing preproenkephalin A or parts of this molecule.