FIG. 2.

RNase protection assay for identification of the expression pattern of four NFI genes at different stages of mammary gland development. RNA was isolated from mammary gland of virgin (V), pregnancy day 15 (P), lactation day 2 (L), and involution stage (I) mice and from mouse brain (Br). RNase protection assays were performed using antisense probes for each NFI gene along with a mouse β-actin control. (A) Schematic representation of the genomic structure of three NFI isoforms expressed in the mouse mammary gland during lactation. (B) Lanes 1 to 5 represent the NFI-A, and lanes 6 to 10 represent NFI-B. (C) Lanes 1 to 5 represent NFI-C, and lanes 6 to 10 represent NFI-X. Upper arrows indicate the 486-bp protected band for each NFI gene, and the asterisk indicates the nonspecific bands. The expression of each NFI gene at each developmental stage was analyzed using the PhosphorImager, and the results are graphically represented in panel D. Error bars denote the standard error of the mean (SEM) of three independent determinations. An asterisk above the error bar represents the statistical significance of the data (P < 0.05).