Effect of BS upon the BALB/MK cells transduced with LBmSN On day 1, BALB/MK cells were seeded on a 24-well plate at 1 × 104 cells/well, and 1 × 106 cells of the virus producing cell lines PA317/LBmSN (2 × 105 cfu/ml) and PA317/LXSN (5 × 106 cfu/ml) were seeded in 25 cm2 flasks. On day 2, the media of PA317 cell clones were replaced with EMEM without EGF. On day 3, the media of PA317 cells containing virus were harvested, centrifuged at 10000 rpm per 1 min in Eppendorf centrifuge. The media of BALB/MK cells were replaced with 0.5 ml of virus solution and supplemented with 5 ng/ml EGF and 8 μg/ml Polybrene. On day 4, the media were replaced with fresh EMEM in the following conditions. After 12 days, the cells were stained with Coomassie Blue and photographed. The results are representative of at least three experiments, which gave essentially the same results. (A) BALB/MK; (B) BALB/MK + 500 μg/ml G418; (C) BALB/MK + 8 μg/ml BS; (D) BALB/MK/LXSN + 500 μg/ml G418; (E) BALB/MK/LXSN; (F) BALB/MK/LXSN + 8 μg/ml BS; (G) BALB/MK/LBmSN; (H) BALB/MK/LBmSN + 500 μg/ml G418; (I) BALB/MK/LBmSN + 0.05 μg/ml BS; (J) BALB/MK/LBmSN + 0.1 μg/ml BS; (K) BALB/MK/LBmSN + 0.2 μg/ml BS; (L) BALB/MK/LBmSN + 0.5 μg/ml BS; (M) BALB/MK/LBmSN + 1 μg/ml BS; (N) BALB/MK/LBmSN + 2 μg/ml BS; (O) BALB/MK/LBmSN + 4 μg/ml BS; (P) BALB/MK/LBmSN + 8 μg/ml BS; (Q) BALB/MK/LBmSN + 16 μg/ml BS; (R) BALB/MK/LBmSN + 32 μg/ml BS(S) Five days after the LBmSN transduction, the cells were detached with trypsin and stained with Trypan blue. Left and right sides represent BALB/MK (control) and BALB/MK/LBmSN cells respectively.