Zebrafish as a disease model for studying human hepatocellular carcinoma

Table 1 Advantages and disadvantages of constitutive and inducible expression systems

Expression systems	Advantages	Disadvantages
Constitutive	Well established, commercially available; in vitro and in vivo, successful methodology for expression of transgene	Expression of oncogenes may cause advanced/highly aggressive tumors and early lethality
Heat-shock	Expression of transgene can be induced on a single cell level	Adverse effects that may arise from the heat shock
Cre-loxP	Well established; commercially available; in vivo, successful methodology for expression of transgene	Not all tissue specific promoters are perfectly specific; leaky gene expression; two plasmid system
GAL4/UAS	Well established; in vivo, successful methodology for expression of transgene	In vivo expression of GAL4 can have side effects, probably related to immune and stress responses; two plasmid system
Mifepristone	Well established; in vivo, successful methodology for expression of transgene	Opening and closing of the switch is slow (hours to days); cell permeability of the RU-486 can be restricted
Tet-on/off-inducible	Well established; commercially available; in vitro and in vivo, successful methodology for expression of transgene	Opening and closing of the switch is slow (hours to days); cell permeability of the doxycycline can be restricted; two plasmid system