Performance of FLPe^NLS+ and FLPe^NLS− at different acceptor-to-donor cell ratios and time points.

<p>(<b>A</b>): GpLuc release by proliferating or differentiating co-cultures of myoblasts^GS.GLuc and myoblasts-FLPe^NLS+ (+) or myoblasts-FLPe^NLS− (−) at different time intervals after culture initiation. Myoblasts^GS.GLuc and myoblasts-FLPe were seeded in different ratios (<i>i.e.</i> 95∶5%, 75∶25%, 25∶75% and 5∶95%). At 72 h after cell seeding, the culture fluid was replaced by fresh culture medium with (growth conditions, no differentiation) or without (differentiation conditions) serum. Fourthy-eight h later the culture medium was refreshed once again. Twenty-four h later the culture fluid was harvested for luciferase activity measurement and replaced by the same volume of fresh culture medium. This procedure was repeated every 24 h until 120 h after the first medium change. Bars represent mean ± standard error of the mean (n = 3). (<b>B</b>): Fold change in luciferase activity calculated on the basis of the data presented in (A). For each experimental condition the average light production under growth conditions was the denominator and the mean of the RLUs produced under differentiation conditions was the numerator. RLUs, relative light units; MBs^GS.GLuc, myoblasts^GS.GLuc; MBs-FLPe, myoblasts-FLPe; NLS, nuclear localization signal.