APCDD1 and cancer: While these results stimulate many questions concerning the efficiency of cellular internalization and intracellular stability and the intracellular mechanism of action of the cPs, questions that are being addressed in scheduled experiments, our first screening of these 10 cPs leaves us with a cP, compound 5, that was active against all cancer cells with IC50s lower than 10 μ M, and a cP, compound 7, that inhibited cancer cell growth and was by far the best hTS inhibitor.