Although commonly used as a marker to indicate uptake by macropinocytosis, dextran is likely to enter cells by other pathways that participate in fluid-phase uptake. Certainly, our results with cytochalasin-D show that dextran can enter BHK cells using an actin-independent pathway, as although actin filaments were disrupted by cytochalasin-D, dextran uptake appeared to be unaffected (see Fig. 6D ). Nevertheless, figure 7 shows that at 0.5 h and 2 h post uptake, BTV-1 was co-localised with co-internalised Alexa-568 labelled dextran, which also suggest that BTV-1 may use macropinocytosis or a macropinocytosis-like mechanism to enter BHK cells.