On what date was the asset acquisition that was announced on February 22, 2007 completed?  
CREATE TABLE "table1_1373542_1" (
  "asset_acquired" text,
  "acquired_from" text,
  "date_announced" text,
  "date_completed" text,
  "reported_cost" text
);
SELECT "date_completed" FROM "table1_1373542_1" WHERE "date_announced"='February 22, 2007';