... activation of protein kinase C(PKC) [9]. Links between retinoids and PKC were con-vincingly demonstrated [10], and even pointed to directbinding between PKCs and RA receptors and control of transcriptional ... IMR-32 cell line was main-tained in DMEM ⁄ F12 (1 : 1) (Invitrogen, Basel, Switzer-land), and the murine neuroblastoma N2a and humanembryonic kidney HEK293 cell lines were maintained in DMEM (Sigma-Aldrich, ... lL of lysis buffer for 90 min at 4 °C.Protein complexes were precipitated by adding 40 lLofa50% slurry of protein G Sepharose beads (Sigma-AldrichChemie GmbH, Steinheim, Germany) for 90 min...