Exhibit 4 AMENDMENT NO. 1 TO THE STOCK AND ASSET PURCHASE AGREEMENT AMENDMENT NO. 1 dated August 6, 1999 (this "AMENDMENT"), among SmithKline Beecham plc, a public limited company organized under the laws of England ("SELLER"), SmithKline Beecham...The Stock and Asset Purchase Agreement • August 31st, 1999 • Quest Diagnostics Inc • Services-medical laboratories • New York
