The start sites of the c-kit transcription are the same in cells downregulated (+ stroma) or upregulated (− stroma) for c-kit expression. Start sites of c-kit transcription as defined by RACE-PCR. Start sites mapped at position −72 (TF-1S #MB6), −57 (TF-1S#MB6), and −56 (TF-1 and TF-1S#MB6). No differences were found between our sequences and the sequence published by Giebel et al.24 5′ primers that were positive (+) or negative (−) in giving a signal from RT-PCR are indicated in the sequence.