Susan Lindquist (Whitehead, MIT / HHMI) 1a: Protein Folding in Infectious Disease and Cancer - Cancer In Part 1a, Dr. Lindquist explains the problem of protein folding. Proteins leave the ribosome as long, linear chains of amino acids but they need to fold into complex three dimensional shapes in the extremely crowded environment of the cytoplasm. Since protein misfolding can be disastrous for cells, proteins known as heat shock proteins (HSPs) have evolved to facilitate proper protein folding. Lindquist explains that sometimes the heat shock response becomes unbalanced resulting in human disease. In the case of cancer, HSPs help cancer cells survive many stresses that would typically kill them. In contrast, many neurodegenerative diseases are