containing lentivirus, the cells were switched into fresh MEF media containing doxycycline (2 μg/mL) to activate expression of the transduced genes. After 48 hours in MEF media with doxycycline (Sigma), the media was replaced with N3 media 22 containing doxycycline. The media was changed every 2–3 days for the duration of the culture period. For BrdU experiments, 10μM BrdU was added to the culture media and was maintained throughout media changes until the cells were fixed.
