A contribution to the relationship between tumour cell social behaviour in vitro and malignancy in vivo.

Membrane activity of high malignant (grade IV in the immunogenetic test of malignancy) cells was found to continue along the contacting edge after random collision with normal cells in vitro, as demonstrated by the high resolution time-lapse cinemicrography. This preservation of surface activity was the main difference in social behaviour of high and low malignant rat tumour cells upon random collision with normal cells in four lines of tumour cells investigated.