There are 2 studies that match your criteria.
Criteria: Freq Range=0 - 300 Hz (Static, ELF),Study Type=In Vitro,Study Subtype=Hormone Changes,Status=Ongoing

Details - Project ID 301
Lab	Japan
Study Design	50-60 Hz (ELF) exposure to MCF-7 breast tumor cells and analysis of melatonin inhibbition of growth
Summary	(ongoing)
Citation
Details - Project ID 1210
Lab	Coghill Research Lab, UK
Study Design	ELF exposure to lymphocytes and analysis of melatonin synthesis upon PHA challenge
Summary	Effect on Melatonin Synthesis by Human Peripheral Blood Lymphocytes of Exposure to ELF EM Fields
Citation