Two-dimensional polyacrylamide gel-electrophoresis pattern of U937 and HL-60 cells. (A) U937 cells cultured for 4 and 24 h in the presence or absence of ZEA. (a) control 4 h cells, (b) control 24 h cells, (c) cells treated with 6 μg/ml ZEA for 4 h, (d) cells treated with 6 μg/ml ZEA for 24 h. (Arrow 1) fructose bisphosphate aldolase A, muscle type, lung cancer antigen NY LU1, (arrow 2 and 3) glyceraldehyde 3-phosphate dehydrogenase, (arrow 4) deoxyuridine triphosphate nucleotidohydrolase, mitochondrial precursor. (B) HL-60 cell cultured for 24 h with (right panel) and without ZEA (left panel). There are 22 protein dots of different expression in plasma membrane. The list of proteins identified by LC/MS/MS is shown in Table 1.