“…In particular, polyamine inhibition of phosphoinositidase C activity has been described in permeabilized GH, cells (Wojcikiewicz and Fain, 1988), although other authors have observed enhancements of soluble phosphoinositidase activity by polyamines (Eichberg et al, 1981). Other reported effects of polyamines on the phosphoinositide system include the activation of MODULA TION OF PHOSPffOINOSITIDE HYDROLYSIS 611 phosphoinositide kinases, thereby increasing the radiolabelling of phosphatidylinositol mono-and bisphosphates (Lundberg et al, 1986;Vogel and Hoppe, 1986;Smith and Snyderman, 1988;Wojcikiewicz and Fain, 1988), the inhibition of phosphatidylinosi-to1 bisphosphate phosphatase (Smith and Snyderman, 1988), the activation of inositol 1,4,5-trisphosphate phosphatase (Seyfred et al, 1984), and the inhibition of phorbol ester activation of protein kinase C (Thams et al, 1986).…”