STK38 and sarcomatoid carcinoma: Subsequent immunohistochemical (IHC) analysis of tissue samples from a diverse clinical cohort—including both common renal cancer subtypes (pRCC, ccRCC, chRCC) and rarer malignancies (e.g., multilocular cystic RCC, Bellini duct carcinoma, Wilms tumor, and mucinous tubular and spindle cell carcinoma)—revealed that STK38 was most prominently and specifically overexpressed in pRCC (Fig. 1c–f).