What is the test for a motion to strike a plaintiff in an anti-SLAPP action?

The anti-SLAPP law, Code of Civil Procedure section 425.16 (hereafter section 425.16), provides a summary mechanism to test the merits of any claim arising out of the defendants' protected communicative activities. The law authorizes courts to strike any cause of action that falls within the statute's purview and on which the plaintiff cannot show a probability of succeeding. The special motion to strike remedy applies equally to lawsuits directed at the protected communicative activities of public entities. (Vargas v. City of Salinas (2009) 46 Cal.4th 1, 18.)