2.1. Reagents
Escherichia coli BL21 (DE3) and plasmids containing pET-3c, an
ampicillin-resistance gene, and isopropyl β-D-1-thiogalactopyranoside
(IPTG) were provided by Invitrogen (Carlsbad, CA). Plasmid extraction
and gel recovery kits as well as restriction enzymes and ligase were
purchased from Guangzhou Tianjin Biotechnology Co., Ltd. (China). EGF
were supplied by Jinan University Biopharmaceutical R&D Center
(Guangzhou, China). All other reagents were provided by GBCBIO
Technologies Inc. (Guangdong, China).
NIH/3T3 (ATCC CRL-7724) cells were purchased from Chinese Academy of
Sciences (Shanghai, China) and cultured in RPMI 1640 supplemented with
10% fetal bovine serum (FBS) (Gibco, New York, USA). HaCaT cells (ATCC
CRL-2310) were purchased from Chinese Academy of Sciences and cultured
in DMEM supplemented with 10% FBS. All cell culture plates and bottles
were obtained from Corning Company (Corning, NY).