Identification of genetic variations in the Gli1 exon 1B genomic region. Electropherograms of the sequence analysis of the region spanning the 5' splice site of intron 1B. Genomic DNA from NIH3T3 cells, Ptch1-/- MEFs and wtMEFs was PCR amplified and the products were analyzed by direct sequencing. The dotted line indicates the exon 1B/intron 1B boundary. The triangles highlight the SNP positions. Note the presence of the canonical GT intronic dinucleotide in NIH3T3 cells, the substitution to GC in wtMEFs, and the heterozygous GT/GC pattern in Ptch1-/- MEFs.