Fig. 1.

Keratin 18 (Krt18) mRNA and protein in adult skeletal muscle. mRNA or protein was extracted from tibialis anterior (TA) muscles of 3-mo-old wild-type FVB (WT) mice or FVB mice lacking either Krt18 (Krt18) or Krt19 [Krt19-knockout (KO)]. A: immunoblot of Krt18 shows Krt18 in WT but not Krt18-KO muscle. B: quantitative RT-PCR of mRNA prepared from TA muscle shows ∼500-fold less Krt19 mRNA (blue) and ∼1,000-fold less Krt18 mRNA (red) than Des mRNA (green). A reference gene, Rer1, is included (black). *Lowest detectable level of PCR product (orange line). C: RT-PCR of mRNA prepared from myofibers isolated from dissociated flexor digitorum brevis (FDB) muscles shows a band representing Krt18 mRNA in WT and Krt19-KO mice but not in Krt18-KO mice. Each experiment was repeated at least once to test reproducibility. RFU, relative fluorescence units.