FIGURE 2.

Elp2 mRNA and protein level are transiently increased in IB3-1 cells treated with 4PBA. A, Elp2 mRNA was quantitated by ribonuclease protection in IB3-1 cells treated for the indicated times with 1 mm 4PBA. The hybridization of an 18 S rRNA as an internal standard was constant under these conditions. A representative fluorogram is shown. B, relative amount of Elp2–1 mRNA compared with the zero time point was determined by densitometry of 13 total experiments using 5 independent sets of samples. For analysis, the density of the Elp2 was initially normalized by the density of the 18 S hybridization within the same sample. The relative Elp2/18S density of the 0 h time point was then arbitrarily set to 1.0, and the remaining densities were again expressed relative to this reference density. Means + S.E. are shown, with p values determined by one-way ANOVA in comparison with t = 0. C, representative fluorogram of equal amounts of whole cell lysates of IB3-1 cells treated with 1 mm 4PBA for 0, 2, 4, 8, and 24 h resolved by SDS-PAGE and quantitated by immunoblot using a specific Elp2 antiserum as described under “Experimental Procedures.” D, densitometric analysis (mean ± S.E.) of seven independent time course experiments. In this analysis the density of the 0 h time point was arbitrarily set to 1.0, with the remaining densities expressed relative to this reference density. Statistical significance was determined by a 1-way ANOVA in comparison with t = 0.