Phosphorylation of MEK and ERK by HRF/TCTP. Basophils were stimulated with HRF/TCTP, and then cell lysates were prepared and Western blotted for phospho-MEK and phospho-ERK as described in “Methods.” (A) Representative experiment showing phosphorylation of MEK in an HRF/TCTP-R donor (top row), phosphorylation of ERK in an HRF/TCTP-R donor (middle row), and equal loading of lanes as determined by anti-ERK (bottom row). (B) Phosphorylation of kinetics of MEK in 3 HRF/TCTP-R donors (●) compared with phosphorylation of kinetics of ERK in 2 HRF/TCTP-R donors (○). All stimulation was done with 1.09 μM HRF/TCTP. (C) Dose response of HRF/TCTP-induced MEK phosphorylation in 3 HRF/TCTP-R donors (●). There was no HRF/TCTP induced phosphorylation of MEK in HRF/TCTP-NR donors (□; n = 3). The standard error is represented by the error bars.