Thus, the 5′-upstream sequence of the HbPIP2;1 gene contained the minimal elements reported to be necessary for the accurate initiation of basal transcription in a range of plant species. Several Myb and Myc as well as WRKY cis-regulatory sequences were also identified along this promoter sequence ( Fig. 6A), indicating the possible regulation of the HbPIP1;1 gene by drought and wound stresses. Contrary to the HbPIP2;1 and HbTIP1;1 promoter regions, which were shown to harbor ethylene, auxin, and ABA as well as SA related responsive cis-acting sequences ( Tungngoen et al., 2009), only two hormone-responsive elements could be identified within this HbPIP1;1 promoter fragment: one classical (5′-AWTTCAAA-3′) ethylene responsive element ( Rawat et al., 2005) and one auxin responsive factor (5′-TGTCTC-3′) ( Liu et al., 2005)