This .html output from Rmarkdown that describes the update of invitrodb between versions 4.1 and 4.2. Invitrodb v4.2 represents the second full release of the ToxCast database in a new schema designed to accommodate the R package dependency, tcplFit2, which is used in curve-fitting and hit-calling of multi-concentration response data. This invitrodb schema was beta-tested with our research release of invitrodb v4.0 that accompanied the publication "The ToxCast Pipeline: Updates to Curve-Fitting Approaches and Database Structure" (Feshuk et al., 2023 https://www.frontiersin.org/journals/toxicology/articles/10.3389/ftox.2023.1275980) and release of tcpl v3.0.1.