Table 1.

Synergism analysis of various schedules of administration of bortezomib and X-radiation

Effect level	Combination index*			Combination index*
	SK-N-BE(2c) cells			UVW/NAT cells
	Simultaneous	BZ before	BZ after	Simultaneous	BZ before	BZ after
ED25	1.12	1.16	1.16	1.02	0.90	0.77
ED50	0.94	1.04	0.95	0.95	0.84	0.79
ED75	0.80	0.93	0.78	0.89	0.80	0.80

Asterisk '*’ indicates that the combination index values are means of four experiments. They were derived from median effect analysis, according to independent action model, for three different levels of toxicity and three alternative schedules of administration. CI values < 1 indicate synergy and values > 1 indicate partial antagonism. Administration schedules were simultaneous, bortezomib 24 h before X-radiation (BZ before) and bortezomib 24 h after X-radiation (BZ after). Italicised values indicate synergy.