(A) Western blot analysis of SERCA 2b expression. SERCA 2a/b siRNA induced a down-regulation of SERCA 2b expression. CTL, control; J1, 1 day after transfection; and J3, 3 days after transfection. (B) Cells were seeded in 24-well plates and incubated for 48 h. PNT1A cells were transfected as indicated in the Materials and methods section and then cultured for a further 4 days. The medium was replaced every 48 h. After 4 days, the number of cells in each well was determined by the MTS assay. CTL, control; siRNA, SERCA 2a/b siRNA. (C) Western blot analysis of PCNA expression. SERCA 2a/b siRNA induced a down-regulation of PCNA expression. CTL, control; J1, 1 day after transfection; and J3, 3 days after transfection.