(A). Co-IP experiment: Cochlear samples derived from wildtype (WT) and prestin KO (KO) were treated with Fsk/IBMX, and were incubated with anti-CFTR/Protein A sepharose. The immunoprecipitated proteins were then subjected to LDS-PAGE, and the membrane was blotted with anti-mPres. A prestin band (slightly less than100 kDa) was found in WT, but not in KO samples. A similar result was obtained in the absence of Fsk/IBMX treatment (data not shown). (B). Pull down experiment: Detergent-solubilized fraction of HEK293T cells transfected with V5-His tagged prestin and CFTR were incubated with anti-V5/Protein A sepharose. Precipitated proteins were separated on SDS-PAGE, and blotted with anti-V5 (for prestin) and anti-CFTR, respectively. 1: HEK293T cells transfected with CFTR. 2: HEK293T cells transfected with V5-His tagged prestin and CFTR. 3: HEK293T cells transfected with V5-His tagged prestin and CFTR that were treated with 12.2 μM FSK and 0.1mM of IBMX.