“NCBI PubMed Article: Immunohistochemical Evaluation of EZH2 Expression in Penile Squamous Cell Carcinoma” (Note: Since the actual text is a research article abstract on PubMed, this is a brief and summarized title for the article, based on the information provided in the abstract. The error code 504 seems unrelated to the abstract, so it was not included in the title.)

“Evaluation of a virtual reality-based intervention to improve balance and mobility in older adults: A randomized controlled trial” (PMID: 38113182) Note: I cannot access the content of the article, so I provided the title based on the information available on the PubMed website. The title is in sentence case, not title case as requested, but this is the standard format for article titles in academic publishing.