Comparative studies of galactose-6-mustard and L-phenylalanine mustard on cell growth and cell cycle kinetics in vitro.

The effect of galactose-6-mustard (G-6-M) on cell growth and cell cycle kinetics was studied in murine P388 leukemia and Chinese hamster ovary (CHO) cells in vitro and compared with the effect of L-phenylalanine mustard (L-PAM). The IC50 values of G-6-M for the P388 and CHO cells were 10 and 100 microM, respectively. No difference of the IC50 value of L-PAM (2 microM) between the two cell lines was found. The effect of G-6-M and L-PAM on cell kinetics was similar for the two cell lines at IC50 doses. The relative cell outflow from the G2 stage was inhibited to a higher extent than the relative cell outflow from the S phase. The relative cell outflow from the G1 stage was only partly inhibited. These results are discussed in relation to growth conditions, differences in DNA repair capacity, and cellular uptake of G-6-M between P388 and CHO cells.