Genentech Posts 50 Percent Rise in Profit  NEW YORK (Reuters) - Genentech Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=DNA.N target=/stocks/quickinfo/fullquote"&gt;DNA.N&lt;/A&gt; on Wednesday  posted a 50 percent rise in quarterly profit and raised its  full-year earnings forecast on strong sales of its new colon  cancer drug, sending its shares higher in after-hours trading.