Certain nucleotides in the U5-IR loop influence selection of nucleotides at nearby positions. The sequences listed in Table 2 were analyzed to show patterns of selection. Panel A: Effects on selection at position 89. Panel B: Effects on selection at position 91. Panel C: Effects on selection at position 93. These data sets were analyzed using a 2-way chi square analysis, and the obtained p-value is indicated for each panel. A p value of <0.05 is considered significant. The number scale along the vertical axis represents the percentage of clones carrying a particular nucleotide at that position.