Figure 2.
ErbB4 significantly stimulates the mRNA expression of all surfactant proteins. ErbB4-naive Gestational Day 17.5 Type II cells were isolated from HER4heart (−/−) animals transfected with full-length ErbB4 (HER4; black bars) or an ErbB4 mutant lacking the nuclear localization sequence (HER4 muNLS; gray bars). The effects of ErbB4 on the expression of surfactant protein A1 (Sftpa1), Sftpb, Sftpc, and Sftpd were measured by real-time PCR. Full-length ErbB4 induced a significant increase in Sftp mRNA concentrations for all four surfactant proteins (*P < 0.001, **P < 0.0001). Preventing the nuclear localization of ErbB4 significantly inhibited the stimulatory effect of ErbB4 on Sftp mRNA concentrations (+P < 0.001, ++P < 0.0001; n = 3).