Abstract Bottke, D., Koychev, D., Busse, A., Heufelder, K., Wiegel, T., Thiel, E., Hinkelbein, W.
and Keilholz, U. Fractionated Irradiation Can Induce Functionally Relevant Multidrug
Resistance Gene and Protein Expression in Human Tumor Cell Lines. Radiat. Res. 170, 41–
48 (2008). The molecular basis of radiotherapy-related multidrug resistance (MDR) is still
unclear. Here we report on a study investigating the effect of fractionated irradiation on
expression of the MDR-associated proteins P-glycoprotein (P-gp), multidrug resistance …

9573 Background: Radiotherapy (RT) can induce the expression of P-glycoprotein (gene
product of the multidrug resistance [MDR] gene 1), which can lead to a broad cytostatic drug
resistance. The kinetics and the functional consequences of this expression are unknown,
but possibly important for radiochemotherapy (RCT) protocols. We here examined the
kinetics of mRNA and protein expression of 3 important MDR-associated molecules MDR1,
MRP (multidrug resistance-associated protein) and LRP (lung resistance protein), and the …