Fig. 4.

PMA-induced OAT1 ubiquitination by ectopically expressed ubiquitin. (A) OAT1-expressing COS-7 cells were transiently transfected with HA-tagged ubiquitin. The transfected cells were treated with PMA (1 μM) in the presence or absence of the PKC-inhibitor staurosporine (St, 2 μM) for 30 minutes. OAT1 was then immunoprecipitated by anti-myc antibody, followed by immunoblotting (Ib) with anti-HA antibody. (B) the same immunoblot as seen in A was reprobed by anti-myc antibody. (C) densitometry plot of results from (A) as well as from other experiments. The values are mean ± S.E. (n = 3).