A compound of formula I, a stereoisomer thereof, a cis-trans-isomer thereof, a tautomer thereof, or a mixture thereof, or a pharmaceutically acceptable salt thereof, or a solvate thereof for use in treating and/or preventing tumor in a mammal, wherein: R 1 is selected from the group consisting of C 1 -C 6 alkylacylamino, C 2 -C 6 alkenylacylamino, C 2 -C 6 alkynylacylamino, C 6 -C 18 arylacylamino, and C 1 -C 6 alkyl substituted amino; R 2 and R 3 are each independently selected from the group consisting of hydrogen, C 7 -C 24 aralkyl, substituted or unsubstituted C 6 -C 18 aryl, and substituted or unsubstituted C 5 -C 18 heteroaryl, wherein a substituent on the aryl is selected from the group consisting of C 2 -C 6 alkynyl, halogen, C 7 -C 24 aralkyloxy, C 6 -C 24 heteroaralkyloxy, C 6 -C 18 aryloxy, and C 5 -C 18 heteroaryloxy, and a substituent on the heteroaryl is selected from the group consisting of C 7 -C 24 aralkyl, C 6 -C 18 arylacylamino, C 6 -C 18 arylsulfonylamino, C 5 -C 18 heteroarylacylamino, C 3 -C 10 cycloalkylacylamino, C 6 -C 18 arylaminoacyl, C 7 -C 24 aralkyloxy, C 6 -C 24 heteroaralkyloxy, and C 6 -C 18 aryloxy; or R 2 and R 3 together with nitrogen atom to which they are attached form substituted or unsubstituted C 3 -C 18 heterocyclyl; and R 4 is substituted or unsubstituted C 3 -C 18 heterocyclyl, or substituted or unsubstituted C 5 -C 18 heteroaryl; and wherein the tumor is selected from the group consisting of breast cancer, lung cancer, gastric cancer, pancreatic cancer, ovarian cancer, osteosarcoma, angiosarcoma, fibrosarcoma, and other sarcoma; sinus tumor; cancers of ureter, bladder, prostate and other urogenital system; esophageal cancer; liver cancer; kidney cancer; endocrine cancer; skin cancer; melanoma; and brain or central nervous system (CNS; glioma) cancer. R 1 is selected from the group consisting of C 1 -C 6 alkylacylamino, C 2 -C 6 alkenylacylamino, C 2 -C 6 alkynylacylamino, C 6 -C 18 arylacylamino, and C 1 -C 6 alkyl substituted amino; R 2 and R 3 are each independently selected from the group consisting of hydrogen, C 7 -C 24 aralkyl, substituted or unsubstituted C 6 -C 18 aryl, and substituted or unsubstituted C 5 -C 18 heteroaryl, wherein a substituent on the aryl is selected from the group consisting of C 2 -C 6 alkynyl, halogen, C 7 -C 24 aralkyloxy, C 6 -C 24 heteroaralkyloxy, C 6 -C 18 aryloxy, and C 5 -C 18 heteroaryloxy, and a substituent on the heteroaryl is selected from the group consisting of C 7 -C 24 aralkyl, C 6 -C 18 arylacylamino, C 6 -C 18 arylsulfonylamino, C 5 -C 18 heteroarylacylamino, C 3 -C 10 cycloalkylacylamino, C 6 -C 18 arylaminoacyl, C 7 -C 24 aralkyloxy, C 6 -C 24 heteroaralkyloxy, and C 6 -C 18 aryloxy; or R 2 and R 3 together with nitrogen atom to which they are attached form substituted or unsubstituted C 3 -C 18 heterocyclyl; and R 4 is substituted or unsubstituted C 3 -C 18 heterocyclyl, or substituted or unsubstituted C 5 -C 18 heteroaryl; and wherein the tumor is selected from the group consisting of breast cancer, lung cancer, gastric cancer, pancreatic cancer, ovarian cancer, osteosarcoma, angiosarcoma, fibrosarcoma, and other sarcoma; sinus tumor; cancers of ureter, bladder, prostate and other urogenital system; esophageal cancer; liver cancer; kidney cancer; endocrine cancer; skin cancer; melanoma; and brain or central nervous system (CNS; glioma) cancer. <EOS>