sentence: NBD-farnesylated Rab1b – CVIL : GDP and Rab1b – CVIL – aGDP ( containing the artificially introduced CaaX-box CVIL at their C termini ) were produced by incubating GGTase I , the Rab protein and NBD-FPP ( 0.5:1:5 ) for 2 h at 25 ° C and confirming the completeness of modification by ESI-MS27 .