GRK6 expression is negatively regulated in a Src-dependent manner. MB cells were transfected with control siRNA or Src siRNA, and then the cells were harvested at 48 h (D556) or 96 h (Daoy) after transfection and examined by real time RT-PCR or Western Blot. (A) Real time RT-PCR shows expression of GRK6 mRNA is significantly increased 1.5 folds in D556 and 3 folds in Daoy by Src siRNA transfection, P < 0.05, respectively. Shown is the representative of three experiments. (B) Western blot shows that the protein level of GRK6 is increased by Src siRNA. (C) Retro-X Tet on Src-inducible stable cell line was treated by 500 ng/ml Dox for 48 h, and then, Src and GRK6 expression were examined by Western blot. Src- induced expression results in decreased GRK6 protein level.