The toxicity and effects of di-n-butyl phthalate (DBP), an endocrine disruptor, on the growth of Chinese cabbage (Brassica rapa var. chinensis) were studied. Etiolation occurred on leaves of Chinese cabbage plant treated with 50 mg/L of DBP for 42 d. DBP even below I mg/L had a significant effect on the concentration of chlorophyll in Chinese cabbage and the biomass showed a severe decrease under treatment with more than 30 mg/L of DBR At a concentration below 1 mg/L of DBR no significant difference in accumulation was found, but treatments with concentration exceeding 10, 30, 50 and 100 mg/L all resulted in significant accumulation of DBR Six protein spots extracted from leaf tissue of DBP-treated Chinese cabbage displaying a differential expression are shown in 2-DE maps. According to proteome level studies, three protein spots were found to increase and were identified, respectively, as acyl-[acyl-carrier-protein] desaturase (acyl-ACP desaturase), root phototropism protein 3 (RPT3) and ferredoxin-nitrite reductase (Fd-NiR). The other three protein spots were found to decrease and were identified respectively as dihydroflavonol-4-reductase (DFR), aminoacyl-tRNA synthetase (aaRS) and ATP synthase subunit beta. The key finding is that the other closely related plant, Bok choy (Brassica rapa subsp. chinensis), the subspecies of Chinese cabbage, respond differently to the same chemicals. (C) 2008 Elsevier B.V. All rights reserved.