nextlimits

Found the function: IS_SUBCATEGORY_OR_SUB

// If is category or subcategory of $cat_id
if (!function_exists('is_category_or_sub')) {
	function is_category_or_sub($cat_id = 0) {
	    foreach (get_the_category() as $cat) {
	    	if ($cat_id == $cat->cat_ID || cat_is_ancestor_of($cat_id, $cat)) return true;
	    }
	    return false;
	}
}