“…M any o f them turned out to be tum or prom oters in the two-stage model o f tumorigenesis on mouse skin [5][6][7], In addition, in current efforts to develop certain Euphorbia spe cies as renewable oleochemical resources, 3-0-hexadecanoylingenol (3-HI) may be considered a potential risk factor o f occupational cancer [8,9]. Also, 3-HI elicits and modulates a variety of bio logical and biochemical responses in various types of cultured cells, including release o f prostaglandin E2 in mouse peritoneal m acrophages [10], induc tion o f Epstein-Barr virus (EBV) associated pro teins in EBV-transformed lym phoblastoid cell lines derived from B urkitt's Lym phom a [11], stim ulation of choline incorporation in the hum an epi thelial cell line HeLa [12], suppression o f sponta neous and prevention o f lymphokine-induced en- Verlag der Zeitschrift für N aturforschung, D-W-7400 Tübingen 0932-0776/92/0700-1026/$ 01.00/0 hancement of rat m acrophage cytolytic activity [13], and induction of differentiation in the hum an promyelocytic leukemia cell line HL-60 [14].…”