Table 1.

IC₅₀ values (µM) for parental and gefitinib- or erlotinib-adapted cell populations in 7-day growth inhibition assays shown in Figure 3 and Figure 4. In case of drug combinations, IC₅₀ values are shown for each drug; fold change in IC₅₀ relative to parental cells shown in parentheses (italicized). IC50 values for senexin B in SKBR3 cells could not be determined due to the low extent of growth inhibition.

	BT474-Par	BT474-GefR	BT474-ErlR	SKBR3-Par	SKBR3-GefR
Gefitinib	0.140	0.973 (6.95)	0.863 (6.16)	0.619	1.530 (2.47)
Senexin B	1.547	2.430 (1.57)	2.561 (1.66)	N/A	N/A
Senexin B + Gefitinib (1:1)	0.087/0.087	0.510/0.510 (5.86)	0.612/0.612 (7.03)	0.403	0.644 (1.60)
Erlotinib	2.489	7.329 (2.94)	8.520 (3.42)	2.478	3.437 (1.39)
Senexin B + Erlotinib (1:5)	0.351/1.753	0.473/2.124 (1.35)	0.915/4.577 (2.61)	0.258/1.292	0.328/1.641 (1.27)