Cloning of IL-2 gene in expression vector. A, amplification of IL-2 gene by PCR with different MgCl2 conc. and temperature gradient, Lane 1: 1kb DNA ladder, Lane 2-5: 1.5, 2.0, 2.5 and 3.0mM MgCl2 at 62°C, Lane 6-9: 1.5, 2.0, 2.5 and 3.0 mM MgCl2 at 65°C. B, restriction digestion of pTz57R/IL-2 recombinant plasmid, Lane 1: 1kb DNA ladder, Lane 2-4: Double digested plasmid with EcoRI/XhoI restriction enzymes. C, restriction digestion of pET28a(+) isolated from DH5α, Lane 1: 1kb DNA ladder, Lane 2: Uncut pET28a(+), Lane 3: Cut pET28a(+) by using EcoRI and XhoI restriction enzymes. D, restriction digestion of recombinant pET28a (+)/IL-2, Lane 1: 1kb DNA ladder, Lane 2: Restriction digestion showing two fragments i.e. ~5326 bp pET28a and ~492bp IL-2.