The P{αTub84B(FRT.Myc)GAL4.Bb} construct contains the αTub84B promoter fused to FRT sequences, followed by the entire open reading frame of Myc, followed by the y open reading frame fused to a tubulin trailer, followed by FRT sequences and sequence encoding a GAL4 driver.
The αTub84B promoter drives expression of an in-frame FRT sequence followed by the entire open reading frame of Myc.