Table 3. Efficiency of R-tam and E25K/K27E Compared to Apamin on SK3 Current and SK3-Dependent Cancer Cell Migration^a.

Peptide	% inhibition of SK3 current	EC50 pM	total% inhibition of cell migration decreased on MDA-MB-435s	% inhibition of SK3 dependent cell migration
r-tam	25	2600	No effect	No effect
E25K/K27E	73	380	45.9	76.5
Apamin	Control*	360	48.6	81

^aR-tam and E25K/K27E were used at 1 nM concentration, while apamin was used at 100 nM as a control*. The % of SK3 inhibition corresponds to the ratio of the amplitude of outward currents blocked by 1 nM compounds to the amplitude of the current in the absence of compounds. The % of SK3-dependent cell migration was determined on MDA-MB435s cells and corresponds to the ratio of the total number of migrating cells in the presence of compounds to the total number of migrating cells in control experiments of SK3+ cells and normalized to the full SK3-dependent capacity of cells to migrate (60%).