Induction of specific protein tyrosine phosphatase transcripts during differentiation of mouse erythroleukemia cells

We reported previously that most of the phosphotyrosine-containing cellular proteins were quickly dephosphorylated at the very early stage of erythroid differentiation of mouse erythroleukemia (MEL) cells. These and other experimental results implicated a specific protein tyrosine phosphatase(s) (PTPase(s)) involved in the commitment of the erythroid differentiation. We have investigated the pattern of transcripts of PTPases during MEL cell differentiation and found that while the transcripts of most PTPases were unchanged or undetected in the cells, transcripts for two PTPases (PTPβ2 and RIP) exhibited distinct patterns of induction at a very early stage of differentiation. Some of the mutant cells defective in differentiation did not show the induction of these PTPase transcripts. We discuss the possible role played by the PTPases in the commitment of MEL cell differentiation.