Sarah Palin's potential mother-in-law, Sherry Johnston, appeared alone at an Alaska court to plead not guilty on Monday to six felony counts of possessing and selling OxyContin. Johnston, who admitted to selling OxyContin pills to an informant, received a public defender for the case. The 42-year-old is the mother of Wasilla teen Levi Johnston, the father of 17-year-old Bristol Palin's newborn baby.