Nuclear transport as an ultimate step of multidrug resistance.

Adriamycin (ADM) incorporation into nuclei of whole multidrug resistant (MDR) CEM cells is lower than into sensitive ones (S), that is mostly thought to be the consequence of a decrease of drug related to the activity of the multidrug resistance plasma membrane protein P 170. Isolated nuclei of the lymphoblastic tumor cell line CEM, which structures were controlled by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal microscopy, where incubated with 10(-6) mole/l of ADM. Incorporation into DNA was quantified by spectrofluorimetry.