Induction of 73-kDa and 90-kDa heat shock protein expression in HL60 cells during differentiation.

We investigated the expression of heat shock proteins HSP73 and HSP90 in human promyelocytic line HL60 during their differentiation induced by phorbor ester and all trans retinoic acid (ATRA). Polyclonal antibodies which had been raised against HSPs purified from bovine brains were used to detect human HSPs. Semiquantitation of HSPs was performed by immunoblotting. Induction of monocytoid and granulocytoid differentiation with phorbor ester and ATRA was accompanied by increased expression of HSP73 and HSP90 with distinct kinetics. Increased expression of both HSPs was confirmed by immunocytochemical studies. Our results suggest that HSP73 and HSP90 may be involved in differentiation of HL60 cells.