Up-regulation of serine/threonine protein phosphatase type 2A regulatory subunits during methylprednisolone-induced differentiation of leukaemic HL-60 cells

Serine/threonine protein phosphatase 2A (PP2A) may play a role in leukaemic cell differentiation of the HL 60 myeloid leukaemic cell-line after methyl prednisolone induction. We have investigated the specific enzyme activity a nd expression of catalytic and regulatory subunits of PP2A. The resulting s pecific enzyme activity and immunoblots showed an increase in enzyme activi ty and the expression of regulatory subunits after methylprednisolone treat ment. There was no change in the expression of PP2A catalytic subunits. It is suggested that the effect of methylprednisolone on leukaemic differentia tion may be the result of PP2A upregulation.