Fig. 5. Polysomal profiles from control MCF-7 cells treated with DMSO vehicle (top) and treated with 10 µM 15d-PGJ2 (bottom). The A254 of each fraction from a sucrose gradient (fraction #1 representing the top of the gradient) was determined (), and isolated RNA was subject to Northern blot analysis to determine which fractions contained cyclin D1 (A) or ß-actin (B) mRNA (). The position of free ribosomes was determined by ethidium bromide staining of the Northern gels. Fraction #3 within this region contained 40S subunits; fractions #4, 5, and 6 contained 60S subunits and 80S ribosomes, incompletely resolved from each other.