BT474, MDA-MB-361, and T47D cells were transduced with an expression cassette encoding Gluc and GFP separated by an internal ribosomal entry site, using a lentiviral vector as previously described (43 (link)). All cell lines, purchased from the American Type Culture Collection, were authenticated (Cell Check). BT474-Gluc and T47D-Gluc cells were maintained in RPMI 1640 supplemented with 10% (v/v) fetal bovine serum (FBS) (Atlanta Biologicals). MDA-MB-361-Gluc cells were maintained in Dulbecco’s modified Eagle’s medium/F12 supplemented with 10% (v/v) FBS.