Tissue culture
HEK 293F (HEK) cells (Thermo Fisher Scientific) were cultured in FreeStyle 293 Expression Medium (Thermo Fisher Scientific) supplemented with penicillin-streptomycin (0.2 U/mL) (Thermo Fisher Scientific). CHO-S cells (Thermo Fisher Scientific) were cultured in FreeStyle CHO Expression Medium (Thermo Fisher Scientific) supplemented with L-glutamine (8 mM, Thermo Fisher Scientific) and penicillin-streptomycin (0.2 U/mL). All cells were grown at 37°C and 5% CO2with rotation at 125 rpm in a humidified atmosphere. Transfections were incubated in the same growth conditions. HEK cells were not subject to more than 25 passages, whereas CHO cells were studied below 10 passages to mitigate cell clumping. All cells were grown to a density of 1.2×106 cells/mL and diluted to 1.0×106 cells/mL on the day of transfection.