PGP and neoplasm: Consequently, the differences in the size of the KB-V1 tumors between the UIC2 and UIC2+CsA treated animals and the lack of the KB-V1 tumors in 52% of these animals (Fig 4A and B) argue against the above assumption and suggests that the stronger Pgp inhibitory effect of the UIC2+CsA combination mediates the anti-tumor effect at least in part.