Fig. 1. Directional migration of cells in a hyaluronan gradient. The directional migration of MDA-MB-468 and MDA-MB-231 cells was assayed in a Dunn chemotaxis chamber. The gradients employed were 0.25% to 10% FBS, 0 to 400 µg/ml umbilical cord hyaluronan, 0 to 400 µg/ml streptococcal hyaluronan or no gradient (0.25% FBS in both chambers). The data are presented as a circular histogram in which each 18° segment represents the total number of cells with an average angle of migration falling within that particular interval. The Rayleigh test for unimodal clustering is used to verify directional migration. If cells show statistically significant directional migration, the mean migration angle is displayed as a red arrow and the 95% confidence interval as a green sector. The number of cells analysed for each treatment is given.