Fig. 1: Transgenic mice with active MEK5 develop sarcomas.
From: Etiopathogenic role of ERK5 signaling in sarcoma: prognostic and therapeutic implications
a Sites in MEK5 (Ser311 and Thr315) were mutated to aspartic acid to create the constitutively active form MEK5DD tagged with a Flag sequence. b pMSG-Flag-MEK5DD was transfected into HeLa cells. Cells were treated with or without 0.1 μM dexamethasone (Dxm). MEK5DD expression and its effect on ERK5 activation were assessed by SDS‒PAGE; MEK5DD and ERK5 were immunoprecipitated from cell extracts with anti-Flag or anti-ERK5 Pro1 antibodies, followed by Western blotting with anti-MEK5 or anti-ERK5 C-terminal antibodies, respectively. c Representative macroscopic images, hematoxylin-eosin and vimentin staining of tumors arising at different anatomical sites in MEK5DD transgenic mice. Atypical epithelioid cells with a haphazard arranged are shown in detail in 40x magnification images. Mammary ducts in the 4567 mouse are indicated by the black arrow. d Expression of MEK5DD (Flag) and ERK5 was assessed by Western blotting in tumors of four different transgenic mice after immunoprecipitation with the anti-Flag or anti-ERK5 Pro1 antibody followed by incubation with the same anti-Flag or anti-ERK5 C-terminal antibody. The dashed lines indicate lanes that were excised from the Western blot. Calnexin was used as a loading control.
