*2.4. Cell Cultures and Spheroid Production*

Cell cultures of human hepatocarcinoma (HepG2) and human embryo kidney (HEK293) cells were obtained from the Russian collection of cell cultures (Institute of Cytology RAS, Saint Petersburg, Russia). The monolayers were cultured in IMDM (HepG2) or DMEM (HEK 293) media, containing 10% embryonic calf serum (Thermo Fisher Scientific, Waltham, MA, USA) and 100 u/mL of penicillin and streptomycin (Thermo Fisher Scientific, Waltham, MA, USA) in an atmosphere of 5% CO2 at 37 ◦C.

To obtain spheroids (3D culture), Corning ® spheroid microplates 96 well black/clear bottom round ULA (Ultra-Low Attachment surface) (CLS4515-5EA) (Corning, Corning, NY, USA) were used. Cells of the HepG2 and HEK 293 lines were seeded at a dose of 300 and 600 cells, correspondingly, per well. The spheroids were cultured for 7 days with daily imaging using a ZEISS Axiovert 200 m microscope (Carl Zeiss AG, Oberkochen, Germany), equipped with an AxioCam MRm camera (Carl Zeiss AG,

Oberkochen, Germany) and a CO2 Incubator XL-3 (PeCon GmbH, Erbach, Germany). Measurements of spheroids were performed using AxioVision program.
