Expression of PTP35, the murine homologue of the protein tyrosine phosphatase-related sequence IA-2, is regulated during cell growth and stimulated by mitogens in 3T3 fibroblasts.

Protein tyrosine phosphatases (PTPases) have been implicated in the control of cell proliferation and differentiation. To isolate new members of this family potentially involved in cell growth regulation, we looked for PTPase sequences differently expressed in proliferating or quiescent NIH 3T3 fibroblasts. The full-length cDNA of one of these growth-regulated genes, named PTP35, was isolated from a 3T3 library and found to encode the murine IA-2 PTPase-related sequence. Endogenous PTP35 mRNA steady-state levels were found to be strictly regulated during cell growth in 3T3 fibroblasts, being high in actively cycling cells and barely detectable in density-arrested cells. Both PTP35 mRNA and protein levels could be induced in quiescent cells by mitogenic stimulation. The growth factor specificity and kinetics of this induction were analyzed in detail.