A CyO derivative in which P{dpp-Sal20} (a 20 kb transposon from ca. 72 to ca. 92 on the molecular map of dpp (FBrf0051824) that covers all functions mediated by the dpp^Hin and dpp^shv region is inserted into CyO (polytene insertion position unknown). CyO-P20 completely suffices for dpp function, even in the absence of any other copies of dpp in the genome i.e. it acts as if it is disomic for the dpp^Hin+ function.