In Central Hudson Gas & Elec. Corp. v. Public Serv. Commn. (447 US 557, 566 [1980]), the Court set out a four-part test for reviewing a regulation that impinges on commercial speech: "[1] the speech must concern lawful activity and not be misleading. [2] Next, we ask whether the asserted government interest is substantial. If both inquiries yield positive answers; [3] we must determine whether the regulation directly advances the governmental interest asserted; [4] whether it is not more extensive than is necessary to serve that interest." "The four parts of the Central Hudson test are not entirely discrete. All are important and, to a certain extent, interrelated." (Greater New Orleans Broadcasting Assn. v. United States, 527 US 173, 183 [1999].) The test still governs the review of restrictions on commercial speech. (See, supra, at 184.)