ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism; ATP-Binding Cassette Transporters/metabolism; Drug Resistance, Neoplasm; Piperazines/pharmacology; Sulfones/pharmacology; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters/genetics; Administration, Oral; Animals; Antineoplastic Agents/administration & dosage; Antineoplastic Agents/blood; Antineoplastic Agents/pharmacokinetics; Area Under Curve; Brain/drug effects; Brain/metabolism; Cell Line, Tumor; Cell Proliferation/drug effects; Chromatography, High Pressure Liquid; Colonic Neoplasms/drug therapy; Colonic Neoplasms/metabolism; Colonic Neoplasms/pathology; Docetaxel; Dose-Response Relationship, Drug; Mice; Mice, Inbred BALB C; Mice, Knockout; Piperazines/administration & dosage; Purines/administration & dosage; Purines/pharmacology; Sildenafil Citrate; Sulfones/administration & dosage; Taxoids/administration & dosage; Taxoids/blood; Taxoids/pharmacokinetics; Topoisomerase I Inhibitors/administration & dosage; Topoisomerase I Inhibitors/blood; Topoisomerase I Inhibitors/pharmacokinetics; Topotecan/administration & dosage; Topotecan/blood; Topotecan/pharmacokinetics; Tumor Burden/drug effects; Vasodilator Agents/administration & dosage; Vasodilator Agents/pharmacology