Prolactin stimulation of tyrosyl phosphorylation of Shc proteins in Nb_2 lymphoma cells, but not mammary tissues

摘要

Prolactin (PRL) stimulates lactogenesis in mammary cells and mitogenesis in a variety of cell types including Nb_2 cells. Studies indicate that a different composite of signaling pathways is involved in the PRL stimulation of mitogenesis as compared to lactogenesis. In the present studies, PRL is shown to stimulate the tyrosyl phosphorylation of all three isoforms of Shc proteins in Nb_2 cells (mitogenesis), but not in the mammary gland. Maximal phosphorylation of the Shc proteins is expressed between 10 and 15 min after a 50-ng/ml PRL treatment. In addition, there is an increased association between the Grb2 protein and Shc proteins upon PRL stimulation. However, no increased association between JAK2 and Shc proteins was observed in either the Nb_2 cells or mammary tissues.