A.-B. MCF-7 cells were infected with recombinant A5b and A1-containing AAVs. The A5b and A1 inserts were cloned in pAAVDJ (Cell Biolabs). After two weeks of GCV treatment and double infection (see materiel and methods), spheroid growth was analysed using a bright field Macroscope (Leica M420) (Panel A). The pixel area (right) of each spheroid was determined using Image j (Rasband, W.S., ImageJ, U. S. National Institutes of Health, Bethesda, Maryland, USA, http://imagej.nih.gov/ij/, 1997-2016). Fresh medium was added 1 week after reinfection and spheroids were grown for a further 7 days and imaged a second time (Panel B). All experiments were performed in triplicate and the data are expressed as mean ± s.d. with a pvalue determined by Student's t-test. Scale bars. 100 μm.