Histones and basic polyamino acids stimulate the uptake of albumin by tumor cells in culture.

Basic proteins and polyamino acids are taken up by mammalian cells at rates up to 3000 times greater than serum albumin. When given together with serum albumin they increase the albumin uptake by a factor that correlates with their own rate of uptake and can reach more than 50-fold. The lowest threshold of activity detected (10(-10)M)is comparable to the activities of the most potent membrane-active agents.