U3-1287 downregulates total and phosphorylation of HER3 as well as AKT phosphorylation, but does not inhibit cell proliferation in CtxRclones. (A) U3-1287 alone did not inhibit cell proliferation in CtxR clones. The cell proliferation was measured via crystal violet assay and plotted as a percentage of proliferation relative to the vehicle control cells. Data points are represented as mean ± s.e.m. (n = 3). (B) U3-1287 downregulates total HER3 and phosphorylation of AKT in CtxR clones. Whole cell lysates were fractionated on SDS-PAGE followed by immunoblotting for the indicated proteins. α-Tubulin was used as a loading control.