Time-dependent reporter gene activation in an <i>ex vivo</i> human skeletal muscle cell differentiation system.

<p>(<b>A</b>) Phase contrast microscopy of co-cultures containing myoblasts^FLPe and myoblasts^GS.Luc at a 1∶1 ratio after incubation for 2, 3, 4 or 5 days in growth medium (upper panels) or in differentiation medium (lower panels). (<b>B</b>) Luminometric analysis of cell lysates prepared at 12-hour intervals from co-cultures initiated with 5×10⁴ myoblasts^FLPe and with 5×10⁴ myoblasts^GS.Luc (upper panels) or with 10⁵ myoblasts^FLPe and with 10⁵ myoblasts^GS.Luc (lower panels). The cells were either maintained in growth medium (solid bars) or in differentiation medium (open bars). The relative light units (RLU) are plotted on linear (left panels) and logarithmic (right panels) scales. Bars correspond to mean ± standard error of the mean (<i>n = </i>3).