Subcellular localization of HSEI and HSEII was performed by the method of green fluorescent protein. pEGFP-C2-HSEI AND pEGFP-C2-HSEII were constructed using two sets of primers (HSEI: 5 -GGGGAATT CAATGATATGGTGCTGCAG-3 and 5 -GGGGTCGACAT TTAGCAACATTGCTCTG-3 ; HSEII: 5 -GGGGAATTCA TGGTCGCGCCGGGGCTTG-3 and 5 -GGGGTCGACA TTTAGCAACATTGCTCTG-3 ) and EcoRI/SalI restriction sites of pEGFP-C2. Recombinant vectors were transfected into BxPC-3 cells (BxPC-3 cell is a cell lineage of adenocarcinoma from pancreas) by Lipofectin reagent (Gibco BRL). Cells were imaged 40 hours after transfection on the fluorescence microscope.