LRRK2 and Parkinson disease: However, it remains unclear whether elevated LRRK2 kinase activity in neurons (where it is expressed at low levels) or in immune cells is the key driver of PD pathogenesis.86 Notwithstanding this gap in knowledge, LRRK2 has been proposed as a key target for therapeutic intervention and several kinase inhibitors are at various preclinical stages (Fig. 1).87