DDT1 MF-2 cells, which are derived from hamster vas deferens smooth muscle, contain alpha 1-adrenergic receptors (54,800 +/- 2700 sites per cell) that are coupled to stimulation of inositol phospholipid metabolism. Incubation of these cells with tumor-promoting phorbol esters, which stimulate calcium- and phospholipid-dependent protein kinase, leads to a marked attenuation of the ability of alp...

Macrophages were isolated from poorly immunogenic metastatic sarcomas (mFS6 and MN/MCA1) of C57BL/6 origin. Tumor-associated macrophages (TAM) showed little release of superoxide when exposed to phorbol myristate acetate. When exposed to a phagocytic stimulus (zymosan), TAM released appreciable amounts of superoxide. TAM had a lower number of specific binding sites for phorbol esters than resid...

Mast cell colonies grew in methylcellulose when mouse spleen cells were cultured for 14 days in the presence of medium conditioned by concanavalin A-stimulated spleen cells. Tumor-promoting phorbol esters, 12-O-tetradecanoylphorbol-13-acetate (TPA) and phorbol-12,13-didecanoate, enhanced the concanavalin A-stimulated spleen cell-conditioned medium-induced colony growth of mast cell progenitors....

Tumor-promoting phorbol esters including 12-O-tetradecanoylphorbol-13-acetate (TPA), specific inhibitors for erythroid differentiation in mouse Friend cells, induce a newly identified nuclear protein with a molecular weight of 54,000 (p54) in Friend cells. Phorbol, an analogue of TPA with neither tumor-promoting nor differentiation-inhibitory activity, did not induce p54. In a variant cell line...

Tumor-promoting phorbol esters including 12-O-tetradecanoylphorbol-13-acetate (TPA), specific inhibitors for erythroid differentiation in mouse Friend cells, induce a newly identified nuclear protein with a molecular weight of 54,000 (p54) in Friend cells. Phorbol, an analogue of TPA with neither tumor-promoting nor differentiation-inhibitory activity, did not induce p54. In a variant cell line...

Modulation of the size of the readily releasable vesicle pool has recently come under scrutiny as a candidate for the regulation of synaptic strength. Using electrophysiological and optical measurement techniques, we show that phorbol esters increase the size of the readily releasable pool at glutamatergic hippocampal synapses in culture through a protein kinase C (PKC)-dependent mechanism. Pho...

Application of either phorbol esters or transforming growth factors to normal cells in culture may induce the appearance of a malignant phenotype. Since the mechanism of transformation by both chemical tumor promoters and growth factors is unknown, it was of interest to investigate whether phorbol esters might potentiate the activity of transforming growth factors. The combination of beta-trans...

The effects of adenosine diphosphate (ADP) ribosylation inhibitors on hematopoietic growth factor-induced proliferation were examined. Significant inhibition of interleukin-3 (IL-3), colony-stimulating factor 1, and lung conditioned media-induced clonal agar growth of normal murine hematopoietic cells by 10 mmol/L nicotinamide (NAM), 10 mmol/L 3-aminobenzamide (3AB), and 5 mmol/L N1-methylnicot...

A variety of phagocytosable and soluble agonists stimulate the human neutrophil respiratory burst enzyme, NADPH-oxidase, an activity required for normal microbicidal function. Of these agonists, the phorbol esters, which stimulate diverse systems by their ability to substitute for diacylglycerol to activate protein kinase C (the major phorbol ester receptor), have now been shown to directly sti...