Objective:To establish the granulocyte-differentiation model of the HL60 cells which are treated with All-trans retinoic acid(ATRA)

and to use the modified two-dimensional electrophoresis conditions to analyze the differences of protein expression between treated and untreated HL60 cells.Methods:HL60 cells were induced through treatment with All-trans retinoic acid(ATRA).For selection of the appropriate drug concentration and induction time

MTT and flow cytometry are used to detect the HL60cell proliferation and the expression of differentiation antigens CD11b respectively.Cellular chemical staining was used for the verification of the differentiation of the treated HL60 cells.The protein of HL60 cell lines could be separated by modified two-dimensional electrophoresis(2-DE).PDQuest software was used to analyze the different protein expression between treated and untreated HL60 cells.The protein was analyzed by matrix-assisted laser desorption -time of flight mass spectrometry(MALDI-TOF).Results:ATRA could inhibit HL60 cell proliferation

and with the increase in drug concentration

the effect of inhibiting was more significant.Treated with 2μ M ATRA for five days

there were more than 90% of HL60 cells expressing antigenCD11b.Cellular chemical staining also showed that ATRA could induce HL60 cells to granulocyte cells.By the analysis of modified 2-DE and PDQuest software

25 protein spots was detected in untreated cells

while 15 protein spots was promoted Some of them were oncogene protein and suppressor gene protein

while some of others are involved in apoptosis.Conclusion:ATRA could induce HL60 cells to granulocyte cells in selected drug concentration and induction time.Using the modified two-dimensional electrophoresis conditions

different protein expression can be found from the traditional two-dimensional electrophoresis.