The blocked pinocytic activity of mitotic cells is restored in mitotic-interphase hybrids

During mitosis there is an abrupt inhibition of a wide range of membrane functions, including fluid-phase and adsorptive pinocytosis. We have used cell hybrids formed between mitotic and interphase cells to approach the mechanism of this inhibition. We report that fluid pinocytosis is reactivated in the mitotic partner of hybrids formed between mitotic and interphase Chinese hamster ovary (CHO) cells. It thus appears that the interphase cell provides some necessary element(s) for membrane activity during mitosis. This dominance of interphase membrane properties stands in contrast with earlier evidence that mitotic nuclear properties dominate in similar mitotic-interphase hybrids.