This just in:

Sources confirm to ET that 36-year-old "Samantha Who" star Christina Applegate has been diagnosed with breast cancer.

A rep for the actress tells ET, "Christina Applegate was diagnosed with an early form of breast cancer. Benefiting from early detection through a doctor-ordered MRI, the cancer is not life threatening. Christina is following the recommended treatment of her doctors and will have a full recovery. No further statement will be issued at this time."

The revelation comes shortly after Applegate was announced as one of several celebrities to participate in the upcoming "Stand Up To Cancer" benefit to air on NBC, ABC and CBS on September 5.

The star rose to fame as a teenager on the FOX network's "Married with Children."