Researchers are reporting that galectin-3, a protein that promotes cancer cell growth and is used as a biomarker for heart failure, is linked to tumors associated with two rare genetic diseases. They found that the protein is produced by tumor cells in tuberous sclerosis complex (TSC), a genetic disease that produces tumors in a variety of organs, and lymphangioleiomyomatosis (LAM), a lung disease that typically affects women. This biomarker could be useful for assessing the severity of these two diseases and for evaluating response to treatments, the researchers say. Their study, which was partly funded by NHLBI, appears in the journal eLife.