Two different WritableCellFormat for a single label or cel

Question

I'm writing to write print two text's in the same cell with different WritableCellFormat format, its shown below

lable = new Label(0, 1, "Market: "+someValue,tableHeaderCellFormat);
sheet.addCell(lable);
sheet.mergeCells(0, 1, 0, 1);

Here Market: is like label ,it'll remain same , but someValue is dynamic, I want Market: to be in bold and someValue in normal font style ie. not bold, I want to write both of 'em in the same cell. Any help?