To investigate the potential role of Thr1108 phosphorylation on MRCKβ cellular localization, we used fluorescence microscopy to examine the distribution of wild-type MRCKβ with a carboxy-terminal green fluorescent protein tag (MRCKβ-GFP), and of kinase-dead MRCKβ-GFP K105M, non-phosphorylatable MRCKβ-GFP T1008A and phosphomimetic MRCKβ-GFP T1008E in transfected MDA-MB-231 D3H2LN human breast cancer cells [21]. The gene discussed is CDC42BPB; the disease is breast cancer.