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The mechanisms by which growth factors stimulate metabolism and cell proliferation are largely unknown. Recent evidence suggests that mitogens rapidly activate a Na+/H+ exchange mechanism in the plasma membrane of their target cells, implicating cytoplasmic pH (pH1) as a potential 'messenger'. Indeed, growth stimulation of quiescent fibroblasts leads to(More)
Addition of epidermal growth factor (EGF) to human A431 cells causes a 2-4-fold increase in cytoplasmic free Ca2+ concentration ([Ca2+]i) as measured by quin-2 fluorescence. The EGF effect is rapid but transient: [Ca2+]i reaches a maximum within 30-60 s and then returns to its resting value (182 +/- 3 nM) over a 5-8-min period. The EGF-induced [Ca2+]i rise(More)
The electrical membrane potential (E(m)) and electrical membrane resistance (R(m)) were measured continuously during the first cleavage of Xenopus eggs, using intracellular microelectrodes. A sharp hyperpolarization of E(m) and decrease in R(m) can be observed from 6 to 8 min after the onset of cleavage. This moment coincides with the onset of the insertion(More)
Parathyroid hormone related peptide (PTHrP), first identified in tumors from patients with the syndrome of "Humoral Hypercalcemia of Malignancy," can replace parathyroid hormone (PTH) in activating the PTH-receptor in responsive cells. Although PTHrP expression is widespread in various adult and fetal tissues, its normal biological function is as yet(More)
In a number of cell types, epidermal growth factor (EGF) evokes dramatic morphological changes, cortical actin polymerization, and stress fiber breakdown. The molecular processes by which increased EGF receptor tyrosine kinase activity results in actin reorganization and morphological changes are unresolved. Recently, we demonstrated that arachidonic acid(More)
The cooperative action of 17 beta-estradiol (E2) and polypeptide growth factors in stimulating proliferation of human breast cancer cells in vitro was investigated. To prevent background estrogenic stimulation, only phenol red-free media were used. When cultured in media supplemented with steroid-stripped serum in which all polypeptide growth factor(More)
Differentiated clonal cell lines were isolated from pluripotent P19 embryonal carcinoma (EC) cells treated as aggregates with retinoic acid. Two were characterized in detail. The lines differ in morphology, proliferation rate, the production of plasminogen activator, and in their mitogenic response to insulin but both produce extracellular matrix proteins(More)
Several subclones of the human embryonal carcinoma (EC) cell line Tera-2 can be induced to differentiate in monolayer culture by retinoic acid (RA) to a flattened cell type with reduced growth rate. Using a method based on the transition probability model, we have analysed changes in cell cycle kinetics of Tera-2 cells during the differentiation process.(More)
In this paper we describe the cloning of the mouse Parathyroid Hormone/Parathyroid Hormone related Peptide Receptor (PTH/PTHrPR) cDNA and expression of its mRNA during mouse postimplantation development from day 5.5 until day 15.5 post coitum (p.c.). In support of a model from previous studies, in which parietal endoderm differentiation is regulated by the(More)
Aggregation of pluripotent P19 embryonal carcinoma (EC) cells in the presence of DMSO induces differentiation to various mesodermal cell types, including spontaneously contracting muscle. We have established clonal cell lines from these cultures and characterized one (MES-1) in particular for its response to growth factors. In contrast to the(More)