Fig. (2). Case Study 1: B-Raf – Comparison of intracellular cSTKpep-3 vs. Mek1 protein substrates HEK293 cells were transiently double transfected (1µg kinase DNA and/or 1µg substrate DNA in 6-well dish) as indicated and immunoblotted. B-Raf constructs were combined with either (A) cSTKpep-3 or (B) kinase-inactive, MEK1(KD) protein substrates; (C)-(E) 384-well TR-FRET assays using a transient reverse transfection protocol. (E) B-Raf(WT) and B-Raf(V600E) constructs were cotransfected at 50ng or 25ng with a 2-fold serial dilution of cSTKpep-3 ranging from 25ng (black bar) to 1.5ng (white bar).