First California Bank is laying off 55 employees in its Westlake Village headquarters, a change connected with its acquisition by PacWest Bancorp. The layoffs are effective April 1, according to the Worker Adjustment and Retraining Notification filed with the California Employment Development Department. It was not known what types of positions were being eliminated, said Roger Pondel, a spokesman for First California, owned by First California Financial Group Inc. “The transaction has not closed yet and they are not commenting further at this point,” Pondel said. In November, PacWest, the Los Angeles parent of Pacific Western Bank, announced it was acquiring First California in a deal valued at $231 million. The combined financial institutions will become the eighth largest publicly held bank headquartered in California. More layoffs could occur in the areas where both First California and PacWest have bank branches, which include Camarillo, Glendale and Thousand Oaks. Shares of First California Financial Group fell 5 cents, or less than 1 percent, to close at $8.52 on the Nasdaq.