Table 1.

Synergistic effects of MEK and PI3K/mTOR inhibitors on canine mucosal melanoma cell lines

Cell Line	CI at fa50	CI at fa90
UCDK9M1	0.14	0.09
UCDK9M2	0.065	0.037
UCDK9M3	0.12	0.089
UCDK9M5	0.15	0.024
Jones	0.21	0.03

Combination indices (CI) of Chou‐Talalay computation, shown for 50% and 90% affected fraction (fa) values at 72 h post‐exposure in vitro, for five mucosal melanomas, provide quantitative definition for drug additive effect (CI = 1), synergism (CI < 1), and antagonism (CI > 1) in combination drug therapy.