MMP9 and breast cancer: Based on our recent observation that airway basal cells (BC) have receptors for HIV and HIV binding to BC induces the BC to express and release matrix metalloproteinase 9 by activating the MAPK pathway, a pathway closely linked to NFκB and transcription factors for expression of inflammatory mediators43–46, we hypothesized that the consequences of HIV binding to BC may be more extensive, and that HIV may induce BC to adopt an “inflammatory phenotype,” with expression and release inflammatory cytokines, contributing to the enhanced inflammatory milieu that characterizes the HIV+ lung.