Frequencies of nucleotides surrounding 39 and 59 splice sites adjacent to exons affected by U2AF1 mutations. Exons that were more often skipped (A) or more often retained (B) in U2AF1 mutants were combined into 2 groups, and the splice site consensus sequences were derived. Adjacent splice sites were analyzed as a control set (C). Nucleotide frequencies are represented using WebLogo software. The height of each stack represents the information content of that position in bits. The height of each letter represents the frequency of occurrence of each nucleotide.