Discovered by Italian biologist Ferruchio Ritossa in the 1960s, these molecules are also called heat-shock proteins. Proteins made by many organisms’ (plant, bacteria and mammal) cells when those cells are stressed by environmental conditions such as certain chemicals, pathogens, or heat. When corn/maize {Zea mays L.) is stressed during its growing season by high nighttime temperatures, that plant switches from its normal production of (immune system defense) chitinase to production of heatshock (i.e., stress) proteins, instead. Stress proteins are also produced by tuberculosis and leprosy bacteria after these bacteria have invaded (i.e., infected) cells in the human body, in an attempt by those bacteria to mimic the stress proteins that (mammal) cells would normally manufacture to repair damage done to the (mammal) cells. This mimicry makes it more difficult for the immune system to recognize and attack those pathogenic bacteria (and/or repair misshaped protein molecules in the body’s cells). In 1996, Richard I. Morimoto discovered that two stress proteins known as HSP 90 and HSP 70 help to ensure that certain crucial proteins in cells are folded into the configuration/conformation needed by that cell.