cells were obtained
from the American Type Culture Collection (ATCC, Manassas, VA). HEK-293
derivative lines 293pTP and 293 RAPA cells were previously characterized.55 (link),56 (link) Mouse mesenchymal stem cell (MSC) line iMEFs was previously characterized.57 (link),58 (link) All cell lines were maintained in DMEM supplemented with 10% fetal
bovine serum (FBS, Gemini Bio-Products, West Sacramento, CA), containing
100 U/mL penicillin and 100 μg/mL streptomycin, at 37 °C
in 5% CO2 as described.21 (link),59 (link),60 (link) All restriction endonuclease enzymes were purchased
from New England Biolabs (NEB, Ipswich, MA). Blasticidin S was purchased
from InvivoGen (San Diego, CA). Unless indicated otherwise, other
reagents were purchased from Sigma-Aldrich (St. Louis, MO) or Thermo
Fisher Scientific (Waltham, MA).