Acrylamid gel electrophoresis separation of protein extracts after induction of essential protein expression by IPTG. Protein extracts from cell cultures of FabI clone (lanes 1-3), MurA clone (4-6) and TrpS clone (7-9) before adding inducer (1 mM IPTG) (lanes 1, 4, 7), 4 h after induction (lanes 2, 5, 8) and 17 h after induction (lanes 3, 6, 9). Lane 10, protein ladder.