Plasmid construct pSA21 based on pBluescript II KS. Ac5′, actin 5′ flanking region (500 base pairs); Ac3′, actin 3′ flanking region (2000 base pairs); lgl1, ORF of lgl1 (867 base pairs); Amp, ampicillin resistance cassette; ColE1Ori, origin of replication; Sc, SacI; N, NcoI; B, BglII; S, SalI; X, XbaI; Ba, BamHI; K, KpnI. The cassettes constructed in this plasmid are subsequently transferred to amoebic vector pEhAct-Neo (Moshitch-Moshkovitch et al., 1996).