Confocal immunofluorescent analysis of IGROV-1 cells, treated with LY294002 #9901 (50 μM, 3hr; left), insulin (100 ng/mL, 30 min; middle), or Leptomycin B followed by insulin (20 nM, 3hr and 100 ng/mL, 30 min, respectively; right), using FoxO1 (C29H4) Rabbit mAb #2880 (green). Actin filaments were labeled with DY-554 phalloidin (red).
Chemical structure of Leptomycin B
Leptomycin B is supplied as a 200 μM solution in ethanol. All dilutions, except the final dilution, must be performed in ethanol. Final dilutions can be performed in culture media. Working concentrations and length of treatment can vary depending on the desired effect, but 5-80 nM for 3 hours generally inhibits most nuclear export. Soluble and stable in ethanol. Leptomycin B is not stable in DMSO; do not dilute in DMSO.
In order to minimize evaporation, it is recommended that the LMB vial be kept on ice when in use.
Stability Warning: LMB in any quantity is unstable when dried down into a film. Thus, under no circumstances should the solvent be removed from solutions of LMB because rapid decomposition and loss of recoverable material will result.
Store solution at -20ºC. Protect from light. If stored and handled appropriately, it will be stable for 12 months.
Leptomycin B (LMB), originally discovered and utilized as a potent anti-fungal antibiotic from Streptomyces sp., has more recently been identified to inhibit nuclear export of proteins and RNA containing a Nuclear Export Sequence (NES) (1). The mechanism behind LMB's potent inhibition is achieved by specifically binding to chromosomal region maintenance (CRM)/exportin 1 protein; CRM1 binds to ribonuclear proteins containing the NES (1,2). LMB has also been reported to inhibit the degradation and subsequently lead to accumulation of p53 within the nucleus (3) and has demonstrated specific anti-tumor properties, although toxic, at high doses (1-3).
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