Pitstop2 is an amphipathic protein-bound inhibitor of the clathrin terminal domain (IC50=12 μM) with selectivity. Pitstop2 severely interferes with receptor-mediated endocytosis, HIV entry and synaptic vesicle cycling. Pitstop2 has antitumor activity.

METHODS: HeLa cells were pre-incubated with Pitstop2 (10-30 µM) for 15 min, followed by incubation with Alexa568-Tf for 15 min, and transferrin (Tf) uptake was detected by live cell microscopy.
RESULTS: HeLa cells efficiently internalized Tf into perinuclear circulating endosomes when exposed to Alexa56-Tf. Preincubation of HeLa cells with Pitstop2 resulted in a dose-dependent inhibition of Tf uptake with IC50 values of 12-15 µM, which was very similar to that measured by in vitro blockade of the function of lattice protein TD. [1]
METHODS: Asynchronously growing HeLa cells were treated with Pitstop2 (0.001-100 µM) for 6 h and assayed for mitotic index.
RESULTS: Acute treatment of HeLa cells with Pitstop2 for 6 h resulted in a significant increase in mitotic index, suggesting that Pitstop2 activates the SAC. The effect of Pitstop2 on mitotic index was concentration-dependent, and significant at concentrations as low as 0.01 µM. [2]