Fig. (3) The T261G mutation of WNK4 confers kinase inhibitor sensitivity. A. Oocytes were injected with NCCT wt alone or in combination with either WNK4 wt or WNK4 T261G. The ²²Na⁺ flux assay was then performed with or without 0.5 or 5 µM of each SB compound. * P<0.0001 vs NCCT alone. B. Confocal microscopy of the fluorescent signal from eCFP-NCCT showed that changes WNK4-induced ²²Na⁺ flux were accompanied by parallel changes in surface membrane expression of the cotransporter. * P< 0.05 vs assay without an SB inhibitor.