Epidermal and transforming growth factors modulate secretion of a 69 kDa phosphoprotein in normal rat kidney fibroblasts

AbstractOur study shows that the secretion of a major non-glycosylated, phosphoprotein of 69 kDa (pp69) is a specific marker for non-transformed NRK-49F cells. Treatment of NRK-49F cells with EGF alone or with different combinations of EGF plus TGF-β modulates the secretion of pp69, suggesting its relationship with cellular proliferation. Antibody raised against pp69 recognizes, in addition to pp69, another major phosphoprotein of 62 kDa (pp62) secreted by RR1022 and spontaneously transformed NRK-49F cells. Immunoprecipitation of total cell lysates from both NRK-49F and RR1022 cells with anti-pp69 antibody detected only pp69. These observations suggest a precursor-product relationship between pp69 secreted by non-transformed NRK-49F cells and pp62 secreted by transformed cells