The HL-60 cell line of human acute promyelocytic leukemia origin, is composed of cells which express phenotypic characteristics of promyelocytes (1). It can be induced to differentiate into cells which have acquired many morphological, cytochemical and functional properties of mature granulocytes when cultured in the presence of retinoic acid (RA) (2). These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.