What is the burden of a defendant in the anti-SLAPP analysis?

In analyzing a defendant's burden under the first prong of the anti-SLAPP analysis, "the critical consideration is whether the cause of action is based on the defendant's protected free speech or petitioning activity." (Navellier v. Sletten (2002) 29 Cal.4th 82, 89.) "The anti-SLAPP statute's definitional focus is not on the form of the plaintiff's cause of action but, rather, the defendant's activity that gives rise to his or her asserted liabilityand whether that activity constitutes protected speech or petitioning." (Id. at p. 92.)