Validation of PA clusters in 3′ UTR and intron regions. (a) A schematic view of a novel PA site identified in the 3′ UTR region of the ITBG5 locus. The primer pair used for validation is shown as arrowheads. (b) The results of RT-PCR reactions performed using an upstream primer in together with a junction primer (sequence-specific sequence + poly(T)) or a control primer (only the sequences-specific portion). The amplification product with the correct size is indicated. (c) Validation of a novel intronic PA site at the PRLP1 locus. The same validation strategy was employed as before. Two primer pairs (green and orange) were designed, which use the same downstream junction primer but different upstream primers. (d) The RT-PCR results produced by two different primer pairs (top: orange; bottom: green). A 550bp band, which is shorter than expected size, was detected.