Table 2.

The candidate drugs/agents of antifibrotic activity

Action	Drug/agent	Reference
Sphingosine kinase inhibitor	PF543 (SphK inhibitor)	(Gonzalez-Fernandez et al., 2017)
	SKI-II (SphK inhibitor, non-selective)	(Yang et al., 2013)
	N,N-dimethylsphingosine (DMS, SphK inhibitor)	(Brunati et al., 2008; Wang et al., 2017b; Xiu et al., 2015)
S1P receptor agonist/antagonist	FTY720 (S1PR1 and S1PR3 agonist)	(Brunati et al., 2008; King et al., 2017; Kong et al., 2014)
	VPC23019 (S1PR1 and S1PR3 antagonist)	(Brunati et al., 2008; Yang et al., 2012; 2013)
	SEW2871 (S1PR1 agonist)	(Ding et al., 2016)
	W146 (S1PR1 antagonist)	(King et al., 2017; Liu et al., 2011; Yang et al., 2012; 2013)
	JTE-013 (S1PR2 antagonist)	(Kageyama et al., 2012; Wang et al., 2017a; Xu et al., 2016; Yang et al., 2015)
	Suramin (S1PR3 antagonist)	(Li et al., 2009a; 2009b)
	KRP203 (FTY720 analog)	(Kaneko et al., 2006; Khattar et al., 2013)
	CAY-10444 (S1PR3 antagonist)	(Yang et al., 2015)
	VPC24191 (S1PR1 and S1PR3 antagonist)	(Al Fadel et al., 2016)
Other inhibitor	Pertussis toxin (PTX; G-protein-coupled receptor signaling inhibitor)	(Brunati et al., 2008; Gonzalez-Fernandez et al., 2017; Yang et al., 2015)
	Melatonin (melatonin receptors agonist)