(A) C3HT101/2 cells transfected with an empty vector (pSuper-retro) or a vector containing an shRNA (Sam68 shRNA) were selected with puromycin, and knockdown populations depleted of Sam68 were identified. The reduction in Sam68 protein was analyzed by immunoblotting with anti-Sam68 (AD1) antibody and anti–β-actin antibodies as loading controls.