MAPK3 and urinary bladder carcinoma: Although total Erk1/2 protein levels exhibited a cell type-specific and drug dose-dependent response similar to the one of α-tubulin and Hsp90, phosphorylated p44/42 levels were severely downregulated in all bladder cancer cell lines, implying the differential control between total and phosphorylated protein destabilization processes in response to the high drug dose treatments.