PBX2 and idiopathic pulmonary fibrosis: We observed that NFkB-p65 (NFKB2) association with FOS decreased over days in cultures, while other motifs generally increased with time, the most striking of which was association with PBX2, a homeobox domain TF that is expressed in human AEC and in primary human alveolar cells in the IPF Cell Atlas [70], but has not been previously characterized during AEC differentiation.