SPY555-actin is a bright & non toxic live and fixed cells F-actin stain based on SPY™ dyes series. Its optimized structure allows quick labeling of F-actin in live & fixed cells with high specificity and very low background. SPY555-actin stains F-actin of live or fixed cells without the need for genetic manipulation or overexpression of fluorescent proteins. Its absorbance and emission are similar to tetramethylrhodamine (TMR). SPY555-actin enables multicolor imaging with SPY505, SPY595, SPY650, SPY700, SiR & GFP. SPY555-actin can be imaged with standard TMR or Cy3 filtersets. It can be used for widefield, confocal, SIM or STED imaging in living or fixed cells and tissue.