FIG. 2.
The mouse Fli-1b transcript is expressed in the leukemic pre-B-cell line 70Z/3 but not in the Friend erythroleukemia cell line 745-A. (A) Schematic representation of the 5′ genomic structure of the mouse Fli-1 gene and of the 5′ ends of known transcript isoforms. Coordinates of transcription initiation sites are given with respect to the last AUG located in exon 1 (AUG +1), usually described to initiate the large FLI-1 protein isoform. Open boxes represent 5′UTR sequences, and the solid box represents the common FLI-1 coding sequence of all Fli-1 transcript isoforms. The sequences which are alternatively coding (−398 and −204 transcripts) or noncoding (transcript Fli-1b) are indicated by hatched boxes. Small horizontal arrows indicate the position of the primers used in RT-PCR. (B) RT-PCR analysis of Fli-1 transcripts expressed in the pre-B-cell line 70Z/3 (lanes 1, 3, and 5) and in the erythroleukemia cell line 745-A (lanes 2, 4, and 6). All the RT-PCR amplifications were performed with equal amounts of total RNA and the common primer 3′ex2 with either primer 5′ex1b (lanes 1 and 2), primer 5′ex1 (lanes 3 and 4), or both (lanes 5 and 6). The lengths of specific Fli-1b cDNA (421 bp) or Fli-1 −398 and −204 cDNAs (258 bp) are given to the right. M, 123-bp ladder. (C) Control Western blot analysis of FLI-1 protein isoforms expressed in the pre-B-cell line 70Z/3 (lane 1) and the erythroleukemia cell line 745-A (lane 2).