Table 1. IC₅₀ values (μM) for the free PS 1 and PS 2 and MAb–17.1A conjugates to the Colo 320 cell line.

	IC50 value
PS 1	11.5±2.1
PS 1–17.1A	2.50a
PS 2	29.0±4.2
PS 2–17.1A	2.2a,b

MAb=monoclonal antibodies; PS=photosensitisers. Values expressed as the mean±s.d. of three experiments.

^aS.d. could not be determined in these cases due to the limited availability of MAb 17.1A.

^bLD₉₀ value.