Abstract: The invention teaches the use of a tricyclic compound for promoting the endocytotic uptake of macromolecular active ingredients.

Abstract: The invention relates to a screening method for discovering auxiliary agents promoting endocytosis of low molecular and/or macro-molecular compounds, especially nucleic acids, in cells, comprising the following steps: a) a yeast strain is selected and yeast cells are cultivated therefrom, b) the yeast cells are incubated with a potential auxiliary agent promoting the endocytosis of low molecular and/or macro-molecular compounds, especially nucleic acids, in cells in addition to a nucleic acid which is replicable and/or replicable in the nucleus and/or in the cytosol of the yeast cells or a low and/or macro-molecular compound, c) the transformation rates or the transport rates into the cytosol or the nucleus are determined and analysis occurs if the transformation rates or transport rates increase in comparison with the transformation rates or transport rates in a reference test in which the auxiliary substance is not used, d) the auxiliary substance is selected or rejected according to the result of the value