A unique protein has been detected that is associated with the differentiation of diffuse large cell lymphoma (DLCL). The WSU-DLCL human cell line was cultured in the absence or presence of the biological agent, Bryostatin 1 (Bryo 1 ). Cellular proteins of parent and differentiated WSU-DLCL cells were analyzed using one- and two-dimensional polyacrylamide gel electrophoresis (ID and 2D PAGE). In the ID PAGE, a unique protein band of molecular mass ~ 47 kD was detected in the differentiated, but not the parent cells. Amino acid sequence of the band indicated the presence of more than one protein. The 2D PAGE analysis showed that one of the proteins of interest had an isoelectric point of 7.4. Partial amino acid sequencing of the spot by tryptic digest showed 100% homology with a-enolase. a-Enolase is a nonneuronal enzyme involved in the glycolytic pathway. This is the first report on the induction of a-enolase in human DLCL after treatment with the natural biological agent, Bryol. We suggest that aenolase may play a significant role in the differentiation of lymphoma in man.