When Aspergillus terreus fungi are grown in laboratory conditions for extended periods, they sometimes undergo changes that make them look different and behave differently. Scientists found that these changed strains become more susceptible to amphotericin B, a common antifungal drug. By studying the genes and proteins in both the original and changed strains, researchers discovered that special proteins called P-type ATPases appear to be responsible for the fungus’s natural resistance to this drug, offering new targets for developing better antifungal treatments.