Upregulation of APOBEC1 and mutational context in esophageal adenocarcinomas. (A) Expression levels of APOBEC1 in a cohort of samples from normal esophagus, Barrett’s esophagus and EACs. The data were extracted from a recent study analyzing the transcriptome of EAC using microarrays , normalized on TATA-binding protein (TBP) expression levels and shown as median-centered Log2 values. Differences between the various sets of data are statistically significant (P < 10−4 by one-way ANOVA coupled with Tukey’s test). Details of APOBEC1 expression patterns from this and other studies are shown in Additional file 3. (B) Sequence context for the mutated cytosine residues in EAC exomes from a recent study . The trinucleotide sequence context is shown for mutations at Cs (All C), at CpG and at non-CpG sites as a weblogo . The expected sequence context for random mutations at cytosines in the human exomes is shown (P < 0.0001 for the first position at non-CpG sites by Chi-square analysis).