Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Geron (Nasdaq: GERN) shares jumped 10% after the company announced that its first patient has enrolled in the company's stem cell clinical trial.

So what: The clinical trial of human embryonic stem cell (hESC)-derived oligodendrocyte progenitor cells will gauge its safety in patients. This is a milestone in possibly finding a cure for paralysis and a big step ahead of the competition for Geron.

Now what: This is the first step in a long road for Geron in clinical trials. The company has very little revenue and is spending about $10 million per quarter in cash flow, so the trial is critical for the company's long-term viability. Today's move is a reaction to great news, but there is a long ways to go for Geron. I would be cautious about buying on the bounce in this stock. 

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Fool contributor Travis Hoium does not have a position in any company mentioned. Try any of our Foolish newsletter services free for 30 days. True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community. The Fool has a disclosure policy.